I thought of using one line on top of another, with different colors and the top line being a dashed one. However, it is a bit of trouble to draw lines that way.
I have actually drawn a part in my electronic symbols library which used that idea. It is a "bridge" that can be placed over a place where two wires cross at a right angle. I used a white line to cover the horizontal line "under the bridge". It works quite well but it is a library "part" that can be used with just one or two mouse clicks. Drawing individual lines that way would require a lot more work and it would need to be done for each multi-color line.
Or now that I think a bit, perhaps at least a horizontal and a vertical line could also be created as parts in that library. I may look at that.
Also some CAD programs allow the user to create new line styles. My old 2D CAD allowed that but I don't think different colors could be used. My new one, QCAD, doesn't seem to do that but it could be suggested to the people in charge of software development.
Oh, and one thing that I like to find in any drafting program that I use is the availability of of the software developers. The lack of that is one big reason why I did not and still do not like the "industry standard" AutoCAD. Sure you could submit suggestions. But you were not allowed to discuss them with the programmers unless they choose to contact you.
The 2D CAD program that I did purchase those many decades ago, EasyCAD, had a discussion group, likt this one, and the head programmer who was also the head of the company WAS PRESENT on that site every day. In fact I once posted about a problem that I found and he became aware of it the same day. When I returned to the group the NEXT day he had posted the availability, at no extra charge, a revised version of the program that completely fixed that problem. THE VERY NEXT DAY!
Neither AutoCAD nor any other expensive 2D CAD program ever gave that kind of service.
When I was looking for a new 2D program, one of the things that I wanted was that kind of commitment from the software engineers. I discovered that QCAD had a similar group and I joined before purchasing the program. I discovered that some of the ones who almost immediately answered my questions, were indeed in that group of programmers. And I could and DID have conversations with them about features in that program. I like that. I think that is important when considering which program to use because sooner or later you are going to find a bug that needs to be fixed or to want a new feature. And, as they said in that motion picture, "Who yo gonna call?"
One trick I use extensively in both Inkscape and EasyEDA for crossing lines, is using a short thicker line segment between the crossing lines in stacking order, parallel to the topmost line, to create very thin apparent "breaks" in the lower line. I believe it makes schematic diagrams easier to read. Consider the following display adapter schematic as an example:
Yes, I do always use the dots to show a connection, and never do four-way connections, but I believe the apparent breaks help perceive the diagram correctly faster.
Note that in the EasyEDA schematic, there is no break in the line: the break is only a visual effect caused by a thick background-colored "art line" placed between the wires in the stacking order. Thus, this is purely a visual effect, and does not affect connectivity or DRC (design rules checks).
KiCAD currently draws all wires separately from art lines, and does not support changing the order in which they are drawn (although the file format specifies such an order).
In the above schematic, I've also used the color of the wires to roughly group their purpose: black for ground, red for supply, green for parallel bus data lines, and blue for various other logic level signals. I'm sure it would not pass a professional review, and proper EE PCB designers would laugh at it, but as an illustration/schematic for hobbyists, it for sure works. (Although I'd use a proper current source for the backlight LEDs instead of a 25 ohm resistance, as discussed in one of the threads I started about driving backlight LEDs, with options to balance the current if the four backlight LEDs weren't matched well enough. And some of the not connected logic pins might be better tied to ground or VCC, depending on the display controller chip preferences.)