Here is a tutorial on how to copy your google site:
Make a copy of your site, you can then use this to play with colours and themes or change the url....
It's easy as 1, 2, 3!
1 Once you are logged in to your googles site click on more actions then click on manage site.
2 Click on the General link on the left of the screen, then scroll down to the bottom of the page.
3 Click on copy this site, fill out the new name field, decide if you want revisions and sharing linked to the copied site, enter the verification catcha code then click on copy site.