Changing the backcolor of a button from a new form that's fired from the clicked button.

I've a main form that contains 4 buttons, when i click these buttons (each of them are always clickable), they creates a new form (using newform.show()). After i close the new created form (with clicking the Save/Ok button) i want the button's (the button that fired this form) backcolor changed after i  close the new created form. How can i make it?