There are various options and there are some speciality tints too. Rustoleum Rocksolid has some good options

There are 3 colors of pretinted: grey, mocha, and tan

http://www.menards.com/main/p-2765847.htm?cm_vc=PDPZ1

http://www.menards.com/main/search.html?search=rocksolid+garage

Otherwise there are lots of other tints that you can add to a clear base. This link is the kit for obsidian.

http://www.menards.com/main/p-2765821-c-8022.htm?tid=1602039543339560932

Other tints

http://www.menards.com/main/search.html?search=rocksolid+tint

How about the beige epoxy with blue, gray and white flakes? The flakes are scattered onto the surface after you roll out the paint in an area and before it dries. It makes the paint job more attractive and helps to mask any imperfections in the floor that would be made more obvious by the paint alone. Bags or containers of the flakes are found near the epoxy paint at HD, Lowes, etc.

Thank you so much that's is a very good idea....thanks again

this comment was for Randy427. Thanks again. love your idea..