Pretty sure in that new appearance guideline that was posted here the other day it says clean or polishable with slip resistant footwear. Nowhere does it say it has to be boots nor leather.
Edit:
Edit 2 Electric Boogaloo: Employees should wear footwear appropriate for their work environment. Professionalism, comfort and safety should be taken into consideration. Regardless of the work environment, shoes must be sturdy, slip resistant, clean or polished and in good condition. For safety reasons, open toe shoes should not be worn in operational warehouses and flip flops are not an acceptable form of footwear for any UPS work location.
You can show up wearing the brightest, most flamboyant shoes you want to as long as it meets these guidelines. It doesn't state they need to be black.. You could always claim safety so people can see you better.
