How to add more color options for Fullwidth Sub Menu?

I would prefer to add the ability to customize this on the fly since my organization will be adding several sub menu’s for different events and blogs. If this is something that would need to manually be changed everytime we add a new page that needs a new submenu color, I would like to inquire getting this feature customized for what we need.

Here is the link to the first event minisite (for lack of better term) https://brainxchange.events/enfold-staging/events/ewts-2016/

I’m trying to avoid wordpress multi-site and multiple wordpress installs for each event so that everything stays on our company website. This allows for a more seamless look and navigation. However, as we grow I’m seeing that some customizations will need to be made to the theme to accomodate what we’re looking to do.