Amber's name color being the odd one out was actually intended. It breaks the pattern of following the characters' color themes, unless you take it in terms of her natural hair color. I've considered changing it for ease of recognition, but I know some players have enjoyed making the connection when that element of her character is revealed.
The fact that black and gray don't lend themselves to great visibility in the interface was also a consideration in not changing it, but her apparent breaking of the pattern was something I'd had in mind since before the interface art was designed.