Shoutbox

ignore what i said above its wrong

you can either do what madman said but this will have to be done for each contact

or

you can download Plus! Tweak and edit the "CustNameAttachTagFmt"
to add color click insert and insert the color character before the (!N) and then the number of the color you want it to be
you can also add other items like the persons email into the custom name using the same method