You can click on the name of the cache and it will render it in a separate page. This was how I was able to verify what the colors mean. After running it with my own screen name here is what I figured out:
1. Dark blue - Not found by you
2. Light blue (Cyan) - Found by you
3. Black - Archived
4. Grey - Disabled
Hopefully a legend can be added to the page referencing the different colors and what they mean.