Go into the object class explorer, create a new net class, enter "*ddr3* in the 'Non-member' filter box, add all of the results to the new class, then select that class to in the PCB panel, select all, and assign the override color to all of them at once?
If you pull updates from sch that will wipe out your net class (IIRC), but the override color setting should remain on all of the nets. You can also just delete the class yourself afterward if you don't need it anymore, but seems like it might still be useful?
Sure would be nice if it were possible to use a regular PCB filter to affect what shows up in the PCB Panel though.