If this is a plane on its own layer (ie not a broken up polygon pour over a tracking layer) You can also use plane layers. defined in PCB stackup.
They are drawn negative, so show up nice and see-through when they're holding a single whole board net. (you can also easily cut through those with drawn lines if you want, and assign different nets to different unconnected areas)
You can also use the view setup to make polygon pours shown as draft or invisible.
right click on PCB: options > Show/hide
Or just hit Ctrl+d
Draft View mostly turns the polygon display off, but leaves a basic tint in place, and a few edge details here and there so you know it's still there. Hidden View makes it completely invisible, so isn't recommended if you tend to forget what you've done or you share designs with others. This feature, not used carefully, can really drive someone mad. Especially someone not familiar with the design or with Altium.