I know there's an alternate verb on spraypaint to make it prefix with "Drawn in several colors:" instead of the specific color. But how about a verb to actually have various colors show up on one line. You would use the normal verb to start a new line, then have some kind of verb that appends the new part of the tag and color you're using to the last line that was drawn. It would greatly improve the appearance of multiple color tags for people who wanted to take the effort.