Hi .....,
In Excel 2002 and above you can color individual worksheet tabs.
Select the sheets you want to color by holding down the CTRL key and clicking the tabs.
Right-click the sheet tab and then click Tab Color.
Click the color you want, and click OK.
There are better alternative in my optinion than coloring sheet tabs.
Changing the Colors of Worksheet Tabs (#tabs)
Color Palette and the 56 Excel ColorIndex Colors
http://www.mvps.org/dmcritchie/excel/colors.htm#tabs