To close the loop on this based on the features currently available in Shopify, my question isn’t possible with vanilla Shopify. You can add tags and search by them, or you can add the metafield and have one color per product, but I never found a solution that allowed multiple colors until I installed a filter plugin.
I tried 3 filters which I would regard as top picks. Sparq, BoostCommerce and SoBooster.
Personally for my needs and from an integration point of view, I chose SoBooster for my website
https://apps.shopify.com/ultimate-search-and-filter-1
Please install and try whichever plugins suit your requirements and meet your budget as my situation was a little complicated. I needed something that worked with quick view, wishlists, reviews, social login, rewards and filtering, so it was a in depth task to review these apps and get them working just as I wanted.
I couldn’t be more happy with the solution provided by the team at SoBooster. They spent a fair amount of time making sure everything was integrated and the quick view worked with their collection code.
The important thing for anyone who is going down the same path to remember is that every filter app that I found has custom code to render the collection grid, so won’t just work with any quick view plugin. This was the thing that was the hardest for me.