Good point, Floog'
If you go strictly by the books, everyone on Mars is nude all the time except for weapon harnesses and jeweled ornaments (a fact that has been largely ignored by illustrators and figure manufacturers over the years, for obvious reasons...

).
That being the case, there really are no uniform colors (as no one wears a uniform). I suppose that the flyers of the various Martian city-states might have individual color-schemes, though.
For my own part, I'm saving silver ornaments for the Black Martian Pirates and giving the Red and Green Martians Gold ornaments. I gave John Carter a dark blue tabard in my LPL entry because that's the way he was portrayed in the Marvel Comics adaptation in the seventies, and that seems to be the visual inspiration for the Bronze Age Dead Earth Imperial (Barsoomian) line.
In the figure that I identified as a Panthan (mercenary) in my LPL entry (The guy with the "Bazooka Joe" scarf around his face), I tried to give him much plainer harness, with much less metal and fewer gems to help distinguish him from the others.