Good point. The UDM menu is designed to be 508 compliant, but there are several factors that are at the users discretion that can effect accessibility. One of those is the color choices you make for your specific menu.
As outlined in our accessibility tests: http://www.udm4.com/menu/accessibility/#guideline2
The colors you choose for the menu can impact the accessibility to someone having color deficits. I would suggest trying other color combinations for your menu.