Color will depend on which "version" of Mario you use.
The Donkey Kong Mario from Atari is all red, blue shoes, white face, black beard/mustache.
You can see him on this video
https://www.youtube.com/watch?v=IzI1RBdK2_g
The Mario from old Nintendo games is brown and red, obvious suspenders and hat.
https://cdn02.nintendo-europe.com/me...rMarioBros.jpg
Later Mario, from later games, is red and blue (or black). However, he changes color depending on what his current "power" is (shooting fire, flying, etc).
https://i.ytimg.com/vi/xLIqBe78814/maxresdefault.jpg (plain)
http://emulator.online/nes/super-mar...fb-preview.jpg ("raccoon power"-- on the box it looks blue, on the game it looks black, blue would probably be most recognizable)
Just don't do green, since that is not Mario.
I'm sure that's much more than you wanted to know, but I couldn't help it. I used to spend hours playing those games (when I could get away with it...)