私が　前に習ったのは、

He has had a colorful career. ＞彼は　いろいろな　おもしろい(波乱にとんだ）人生を　歩んできた。

だから、colorful って、変化のある　おもしろいっていうような　意味だとおもいます。

Colorful charcter is a charcter that is full of energy he has alot to show and charcter about him that makes him unique and special.

It can mean many different things it an Expression.