Okay, here's a few I've made for my own use in my world in progress. Maybe they'll be useful for you guys. The set is made around the colours in the beach rocks you can place in your world - dark, medium, and light grey with a touch of warmer tones.
Three colours of stone, to match the different shades in the beach rock: Dark, medium, and light.
Two colours of dirt, somewhat darker and desaturated from the game's originals: Dark and light.
Two colours of grass, also somewhat darker and desaturated: Dark and detail - the detail version has an alpha.
One colour of sand: darker and made to match more closely the colours of the beach rock.
EDIT: Added all of these as terrain paints you can use on your lots too, so if you use these in CAW you can paint areas of your lots to match. Thanks to Inge and Peter for S3OC/S3PE.
All are clearly named. Use and abuse freely, for whatever, however, I don't care.