Assign BackColor of clicked Button

Hi
I’ve got a ascx file, where the C# code is included.
A huge amount of buttons with different background colors are present,
<asp:Button ID="Button1" runat="server" BackColor="#003366" /> . . .where I need to assign the background color of the clicked Button to a Label1.BackColor.
How exactly do I need to assign the background color of the clicked Botton, in one code part, instead of writing as many OnClick-Events as Buttons are present?
Patrick