How to customize the dropdown button appearance in WInForms SplitButton?

//Draws an arrow of the SplitButton
public void DrawArrow(int left, int top, int width, int height, PaintEventArgs e, Color ArrowColor)
{
    int StartPoint = left + 5;
    int EndPoint = StartPoint + width / 2;
    int HeightPoint = height;
    int TopPoint = height / 2 - 6;
    ArrowColorDefault = new SolidBrush(Color.Red);
    e.Graphics.FillPolygon(ArrowColorDefault, new Point[] { new Point(StartPoint, TopPoint ), new Point(StartPoint, TopPoint + 12 ), new Point(StartPoint + 7 , TopPoint  + 6) });
}

'Draws an arrow of the SplitButton
Public Sub DrawArrow(ByVal left As Integer, ByVal top As Integer, ByVal width As Integer, ByVal height As Integer, ByVal e As PaintEventArgs, ByVal ArrowColor As Color) Implements ISplitButtonRenderer.DrawArrow
    Dim StartPoint As Integer = left + 5
    Dim EndPoint As Integer = StartPoint + width \ 2
    Dim HeightPoint As Integer = height
    Dim TopPoint As Integer = height \ 2 - 6
    ArrowColorDefault = New SolidBrush(Color.Red)
    e.Graphics.FillPolygon(ArrowColorDefault, New Point() {New Point(StartPoint, TopPoint), New Point(StartPoint, TopPoint + 12), New Point(StartPoint + 7, TopPoint + 6)})
End Sub