Relationship Colors

I would love it if Relationship fields could transfer colors to the other app.  Currently, we have a separate version of a category field on a whole bunch of apps, because if I change it to a relationship field then I lose the ability to show the color of the category in views.  This is particularly true as it relates to Calendar views where colored bars are extremely visually helpful.  So, I'd love to change the category to a relationship so it won't have to be updated in multiple apps when something changes, but when I do that, I lose all color reference.  Creating some ability to have color transcend apps would be amazing.