Both is easy to be done. For faction names, go to data/text/expanded_bi.txt and change a faction's name to whateaver you please. Of course, in the same file, you should change things like for example, change Makedonian Spy, Faction Leader, Faction Heir, Capital ect. to Pergamon Spy, Faction Leader, Faction Heir, Capital ect..

As for colours, just go to data/descr_sm_factions.txt and find the line of primary faction's colours. It's in rgb values but here is a nice little site with colours and their rgb values.

Hope this helped!