If you need to change button color use ActiveX buttons,
and what you indicate can be done with just one button.
Code:
Private Sub CommandButton3_Click()
' use of only one ActiveX button
With CommandButton3
If .BackColor = vbYellow Then
Range("A4").Formula = "=A2/2"
.Caption = "Current division is by 2"
.BackColor = vbCyan
Else
Range("A4").Formula = "=A2/3"
.Caption = "Current division is by 3"
.BackColor = vbYellow
End If
End With
End Sub