Com esse código vc consegue mudar a cor da aba:
Private Sub TabControl1_DrawItem(ByVal sender As System.Object, ByVal e As System.Windows.Forms.DrawItemEventArgs) Handles TabControl1.DrawItem
'obs: mudar a propriedade drawmode para = OwnerDrawFixed
Dim g As Graphics = e.Graphics
Dim tp As TabPage = TabControl1.TabPages(e.Index)
Dim tc As TabControl = TabControl1
Dim br As Brush
Dim sf As New StringFormat
Dim r As New RectangleF(e.Bounds.X, e.Bounds.Y + 1, e.Bounds.Width + 1, e.Bounds.Height - 2)
sf.Alignment = StringAlignment.Center
Dim strTitle As String = tp.Text
br = New SolidBrush(Color.FromArgb(200, 200, 200))
g.FillRectangle(br, e.Bounds)
g.DrawString(strTitle, TabControl1.Font, Brushes.Black, r, sf)
End Sub
Agora basta adaptar a sua necessidade...
qq dúvida postae
t+