Without looking too deeply - perhaps try revising along the lines of:

Private Sub Worksheet_Change(ByVal Target As Range)
    Dim rngInterest As Range, rngCell As Range
    Dim iColor As Long, fColor As Long
    Set rngInterest = Intersect(Target, Range("L5:GR12"))
    If Not rngInterest Is Nothing Then
        For Each rngCell In rngInterest.Cells
            Select Case rngCell.Value
                Case "D"
                    iColor = 7                        'Pink
                    fColor = 1                        'Black
                Case "N"
                    iColor = 4                        'Green
                    fColor = 1                        'Black
                Case "S", "S10"
                    iColor = 42                       'Turquoise
                    fColor = 1                        'Black
                Case "V"
                    iColor = 40                       'Tan
                    fColor = 1                        'Black
                Case "SH"
                    iColor = 24                       'Ice Blue
                    fColor = 3                        'Red
                Case "SD4", "SD5", "SD6", "SD7", "SD8", "SD9"
                    iColor = 27                       'Yellow
                    fColor = 1                        'Black
                Case "SD10", "SD11", "SD12", "SD13", "SD14", "SD15"
                    iColor = 27                       'Yellow
                    fColor = 1                        'Black
                Case "O", ""
                    iColor = 2                        'White
                    fColor = 1                        'Black
                Case Else
                    iColor = -1
            End Select
            If iColor <> -1 Then
                With rngCell
                    .Interior.ColorIndex = iColor
                    .Font.ColorIndex = fColor
                End With
                Call ClearVacationAudit(rngCell)
            End If
        Next rngCell
    End If
    Set rngInterest = Nothing
End Sub
Sub ClearVacationAudit(rngCell As Range)
    Select Case rngCell.Row
        Case 5 To 12
            Sheets("Audit~Jan~Jun").Cells(200 + 6 * (rngCell.Row - 5), rngCell.Column - 8).Resize(4).ClearContents
    End Select
End Sub