Gmail now lets you define colrs for specific labels.

In the message list, any label that has a color assigned will display in that color. Labels with no color assigned will display as they always did. Here is an example:

To assign colors to a Label, click the Label selector on the left of any Gmail page to display the Labels. Hover your mouse to the right of the Label, and a small triangle will appear. Click it, and a color selector will appear. Select a color, and all messages with that Label will display the Label in that color.

As an added bonus, you can quickly and easily rename the Label using the new "Edit name" menu selection. Just be careful to double-check