To edit the computer registry, first you should log onto your computer with administrative rights.
Click Start button and type regedit in Run option then press Enter for next.
Navigate to this key:
Select the key named Theme from the right-hand side of the window.
Set the Theme to one of the following values to get the color of your choice:
For Blue color scheme: 1
For Silver color scheme: 2
For Black color scheme: 3
Now close the registry editor and restart your computer after any changes to go into effect. You have successfully changed the color scheme of Office 2007 to suit your wish.