[Erwin]

You can do this in many ways.

Make a custom profile field, and make it only modifiable by staff, and not visible to members. Get people to enter their color "blue" or hex code "#000000" in it.

Then in your postbit, replace $post[usertitle] with:

<font color=$post[fieldx]>$post[usertitle]</font>

(x being the custom user profile field id). This way your staff can choose their color.

If you make custom titles enabled, your mods can directly just enter <font color=xxx>Moderator</font> in the custom user title field in their Profile. But then members can do that too then.

There are also hacks available that can do this - do a search for them.