Ok.

I tried it. Here is the code I came up with.


Private Function ApplyColour(ByRef rng As Range, ByVal Id As Long)
'Applies the color to the cells.


    With rng
    
        Select Case Id
            Case 1
                .Interior.Color = RGB(255, 128, 128)
            Case 2
                .Interior.Color = RGB(255, 255, 0)
            Case 3
                .Interior.Color = RGB(0, 255, 128)
            Case 4
                .Interior.Color = RGB(204, 255, 255)
        End Select
    End With
    
End Function
But when I try to run it I get a Compile Error saying "Argument Not Optional" and it's highlighting this part of the call code.
Call ApplyColour(.Cells(ActiveCell.Row, "A").Resize(,5))