Hi there, @meeko . Thanks for reaching out to the Shopify Community with your question regarding color variant swatches. My name is Imogen. It’s nice to meet you!
This functionality isn’t built into the Dawn theme natively, so in order for you to add it to your shop you’re going to need to either add a third party app, or have someone build this functionality for your shop using custom coding.
The easiest way to go about adding this to your store is via the third-party app route. I dug through our App Store and found this page here that has loads of options for you to choose from. I did note that you were looking for something free, so I have two specific options to recommend:
AVIS Product Options - this free app looks to provide you with loads of control with product options and colours. I didn’t see an example of them showing colours on collection page, but it could potentially include this feature. I recommend downloading it, and trying it out!
Swatch King - This is a paid option that absolutely has the feature you’re looking for. This app is not free, but I wanted to recommend it because it’s a safe bet to look into as we know it features the functionality you’re looking for.
If neither of these options are great fits, then definitely explore some of the additional third party apps, or reach out to our Shopify Experts to see if you can hire someone to build this functionality for you!
Do you mind me asking why you’re looking to feature your products in such a way? What sort of products are you selling in your store? I’d love to hear more about your business!