I'm presuming that both the IP address and www.supersup.com are on the same server? If so, it looks like Apache only knows one document root which is the www.supersup.com . When you access the IP address direct, Magento then gets the base URL from it's config and redirects over to www.supersup.com.
If you want a different site to appear on 66.40.46.225 then you will need to set up a vhost for it so Apache knowws how to route it.