Is there a way to change color of only certain region of terrain?

So I want to make my terrain generation not so same all the time. I though of coloring the terrains material but it only will change the color of the material => change color of all terrain with material color of which I want to change. So I want to know if there is a way to color only small parts of terrain?

you can go to the terrain editor and press paint, it will change the mesh but not the texture for changing the texture you add/subtract