This is an extract of some code you can also find on the ExcelVBA site.
To determine  the color  index just use your recorder and add some colors you
would like to use.


With Range("A1")

nr = Range(.Cells(1, 1), .End(xlDown)).Rows.Count
nc = Range(.Cells(1, 1), .End(xlToRight)).Columns.Count

For r = 1 To nr
For c = 1 To nc

If .Cells(r, c).Interior.ColorIndex = ?? Then

ElseIf .Cells(r, c).Interior.ColorIndex = ?? Then

End If

Next c
Next r

End With