Highlighting Labels

I want to highlight all of the labels in the code.
ie.
labelname:

The label name isn't a specific keyword because the user makes it up. The only thing that makes it a label is the colon.

Is there an easy way to do this?

I'm thinking there probably is, and it probably has to do with creating a pattern for it, but I don't know where or what the pattern would be.

Any help would be appreciated.

Dave