Absolutely! The Newtek Shopping Cart has a large number of different "themes" available to customize your cart. In fact, you can even upload custom logos, product pictures, etc. in order to make your storefront your own. However, they're just not installed and available to use by default.
You see, in order to keep the installation of the cart as quick as possible, we only included a few themes and button sets in the default installation of the cart - the rest are zipped up in a file called "UnzipThisForMoreThemes.zip" and stored in the cart's "themes" folder. This doesn't mean you can't use these additional themes, it simply means you will have to "unzip" the file in order to use them.
To do this, you first need to get zip file from your shopping cart to your desktop using your favorite FTP client (e.g., CuteFTP, FileZilla, WS_FTP, etc.). As mentioned, the zipped file resides within the "themes" folder, which is itself within the "images" folder of the Newtek Cart installation (in the image below, taken while using the FileZilla FTP client, the Newtek Cart is installed in a sub-folder called "mycart", so the path to the zip file is mycart-->images-->themes-->UnzipThisForMoreThemes.zip).
Once you get the file to your desktop, you can see...
...that when you go to unzip it, there are 3 folders: images, headers and buttons. These 3 folders will just need to replace the same 3 folders that currently reside in the "themes" folder within your Newtek Cart installation. To move them simply access your cart's installation using your FTP client of choice, navigate to the "themes" folder, and replace the existing folders with the 3 you unzipped to your local machine.
**NOTE: There are a TON of files within these 3 unzipped folders. Therefore, moving them back to your cart installation may take several minutes to complete, especially on a slower internet connection.**
Once you have moved the folders to your shopping cart, the new themes, buttons and headers will be available for use.