An example

'-----------------------------------------------------------------
Private Sub Worksheet_Change(ByVal Target As Range)
'-----------------------------------------------------------------
Const WS_RANGE As String = "H1:H10"    '<=== change to suit

   On Error GoTo ws_exit:
   Application.EnableEvents = False
   If Not Intersect(Target, Me.Range(WS_RANGE)) Is Nothing Then
       With Target
           Select Case .Value
               Case 1: .Interior.ColorIndex = 3    'red
               Case 2: .Interior.ColorIndex = 6    'yellow
               Case 3: .Interior.ColorIndex = 5    'blue
               Case 4: .Interior.ColorIndex = 10   'green
           End Select
       End With
   End If

ws_exit:
   Application.EnableEvents = True
End Sub

'This is worksheet event code, which means that it needs to be
'placed in the appropriate worksheet code module, not a standard
'code module. To do this, right-click on the sheet tab, select
'the View Code option from the menu, and paste the code in.