Different colors for factions

First of all, I'm a total newb when it comes to modding.

I downloaded the Road to Jerusalem Mod and I've got one little problem with it: The colors of the factions on the campaign map aren't unique.
Aragon and England, for example, have both red provinves with yellow borders. Saxons and HRE have black and yellow.

Is it easy to change that? If yes, what file do I need to edit?

I've done a search, but my search-fu was weak. Apologies, if this has already been covered.

Open data/descr_sm_factions (or rtj/data/descr_sm_factions if rtj has it's own folder), change the color. It's in RGB format.