Jedi's use blue/yellow and green. Sith use red.
I mean, look at the Deceived trailer when that ship opens up. Red red red red.
SOME sith/jedi seem to have other colourcrystals and they are often someone special.
And this is the case, because everyone in the game is someone special and powerfull and is a large part of the lore in this game.
So in short, no it is not normal to have whatever colour you want, but you are special.