Use of colors in graph timeline

WCAG 1.4.1 Use of Color requirements state:

1.4.1 Use of Color: Color is not used as the only visual means of conveying information, indicating an action, prompting a response, or distinguishing a visual element. (Level A)

In the Repository -> Graph page, the timeline depends heavily on colors, and it is not clear if the colors are used to communicate any additional information and what that information would be.