How can I list custom post type categories of portfolio

by

Use the following function: wp_list_categories();. You can find more information on the codex.

Here is how to display the list:

<?php $args = array(
    'taxonomy'    => 'portfolio_taxonomy', // your custom post type Taxonomy
    'order'       => 'ASC' // Order of the list
);

wp_list_categories($args); ?>