I am working from middle aged memory
If you start the pcb program & go to file - preferences - colors then all the layer settings colors can be changed from there. (I'm being very American here, I'm getting lots of red squiggles underneath the word [glow]colours[/glow]).
These settings can be saved in a file in the .pcb hidden directory in the home folder and I *think* they are loaded automatically the next time the program starts.
If I use a ground plane then I find it convenient to put it on it's own layer & set it to a slightly different color to the traces on the same side of the board as can be seen in the screenshot posted above.
To do this, BEFORE I start laying out a board design, I need to go to the menu Settings - New lines,arcs clear polygons and then, any ground plane will automatically keep away from traces on the same side of the board, or if I need to lay a new trace, it will push the ground plane out of the way.
If this is done then I can go into file - preferences - layers - groups and set the trace layer & the ground layer to the same group and they will be treated as one entity. The two layers can be displayed or hidden together by either of the layer buttons.
It is sometimes convenient to hide the ground plane temporarily, it just needs to have it's group setting changed & it can be hidden without affecting the traces on the same side of the board.
The only other thing I did was to hack the pcb code & gnetlist scripts to allow 8 trace styles(widths) instead of the standard 4 but that is a whole different ball game for another day.