Color by Group in Properties

[MPetramalo51]

Hi all, 

Apologize if this question is elementary, I'm new to developing custom visuals, and I'm struggling adding color options for each data group. 

I'm currently developing a chord diagram, and I've got the diagram built out in d3, and it shows up in Power BI fine.  But I'm trying to now add the ability for users to pick colors, instead of me just having a list of colors hard coded, or random colors from the color pallette. 

I've been trying to do some research online, but I'm finding what looks like some outdated stuff from a few years ago and its hard to tell what I'm supposed to do.  

Currently: I've just hardcoded a bunch of colors since I'm working with dummy data. 

Goal: Goal being for each group, be able to select a color.  I cant figure out how to iterate over the list of values, and have them show up on the property pane.