If you were asking about the customer-facing order display, yes that's easy. Now modifying the admin panel - that's a bit more tricky.
There's no hooks or templates for this, so you basically have to remove the meta box and replace it with a customized one.
remove_meta_box( 'woocommerce-order-items', 'shop_order','normal');
then re_add it with your own function:
add_meta_box( 'woocommerce-order-items', __('Order Items <small>– Note: if you edit quantities or remove items from the order you will need to manually change the item\'s stock levels.</small>', 'woocommerce'), 'your-function-here', 'shop_order', 'normal', 'high');
Copy the contents of the woocommerce_order_data_meta_box function in writepanel-order_data.php into your own function (put it inside your theme's functsion.php ) and then you can add a category column.