Unfortunately, this is one of the things that we aren't easily able to control.
Active, focus, and hover colors can only be set using a CSS stylesheet which Canvas doesn't allow at the course level. In essence, anything that changes based on any sort of action can only be set using a CSS stylesheet. Therefore, there is not a way to customize the color easily by using the color pickers in Design Tools.
One way around this is by using our Custom CSS feature if you or someone on your team has a deeper knowledge of CSS.