If you have not done so already, you obviously need to download and install The Sims 4 Studio. Make your own Sims 4 CC floors: TS4 Studio Quick tutorial
Paint won’t be your best option if you want to do a recolour, but it will work if you are playing around with making some of your own patterns – which is far easier than it sounds. Once you learn how easy it is, you might never use the in-game floors ever again. In fact, this floor pattern, which you can download on Sims File Share if you like, was made using only Paint.
