This may ahve come up before - it might be worth searching the list...but...
Colours - I think "Taki" has a couple of pics on his site - http://www3.plala.or.jp/takihome
/ . They show three tone Whippets re-armed with japanese MGs. Colours are almost anyone's guess, but I'd be very strongly inclined to favour an Ochre-Green-Brown combination as found on the FTs they imported and later in a diffrent guise on their own tanks.
Don't recall seeing any markings.