Well, there's two ways that will affect how adoptables are shown. One way they are affected is by the template you use on your site. This can change how they are displayed.
Also, in adopt.php there is code that shows how they are arranged on the adopt page. Below is the code that shows adoptables to logged in members, but there is a second set of code that is similar for guests...
PHP Code:
$article_content=$article_content."<p align='center'><b><a href='adopt.php?aID=".$aID."'>".$name.":</a></b></p>
<p align='center'><a href='adopt.php?aID=".$aID."'><img src='".$imageurl."' border='0'></a> </p>
<p align='center'><a href='adopt.php?aID=".$aID."'>Adopt ".$name."</a></p>";
As you can see, there is HTML code in there along with variable names. (The things with dollar signs in front are variables and change based on the adoptable we are showing.)
You can edit that as well to change the look.
Hope it helps,
Brandon