See a list of the ColorIndex and the corresponding color

To see the colors, go to the visual basic editor. Hit the help question mark.

Type ColorIndex. From the list of topics, select the one called "ColorIndex Property". They have a nice visual table at the bottom of this help topic.

You could also build a color table with a quick macro

Public Sub ColorTable()
    For i = 1 To 56
        Range("A" & i).Interior.ColorIndex = i
        Range("B" & i).Value = i
    Next i
End Sub