The default social icons on the Minimal Theme are a flat dark grey and whilst that’s generic enough to cover most stores, others need a splash of colour. If you are one of those stores, not having that option in the theme is a pain. To that end, feel free to take this quick replacement. Download Social Icons for Shopify Minimal Theme.
To use, just upload the image to your themes asset folder, replacing the existing grey icons. See more info on the Shopify ecommerce forum.