With this PrestaShop addon you can define custom graph tags for each product / category / cms pages etc. in your shop. In fact, you can customize appearance of any part of your website on facebook.
module is available here:
mypresta.eu/modules/social-networks/facebook-open-graph-tags.html
Of course if you will not use customized open graph tags - plugin will generate open graph tags automatically based on descriptions, names, and images uploaded to shop. Even with automatic tags products appears much better on facebook!