Custom Post Type page by category

Hi,
I’m using CPT to show categories:

<?php
				//list terms in a given taxonomy using wp_list_categories  (also useful as a widget)
				$orderby = 'name';
				$show_count = 0; // 1 for yes, 0 for no
				$pad_counts = 0; // 1 for yes, 0 for no
				$hierarchical = 1; // 1 for yes, 0 for no
				$taxonomy = 'category';
				$title = 'LISTA';

				$args = array(
				  'orderby' => $orderby,
				  'show_count' => $show_count,
				  'pad_counts' => $pad_counts,
				  'hierarchical' => $hierarchical,
				  'taxonomy' => $taxonomy,
				  'title_li' => $title
				);
				?>
				<ul>
				<?php
				wp_list_categories($args);

				?>

				</ul>

And works fine.. but, I would like to show relative post for each selected category, I try with this:

<?php 

					//Custom Loop
						$args = array(
							'post_type' => 'prodotti_accessori',
							'posts_per_page' => 10
						);

						$loop = new WP_Query( $args );

						//Custom Loop
						if( $loop->have_posts() ) :
							while ( $loop->have_posts() ) : $loop->the_post();
					?>
						<h2><?php the_title(); ?></h2>
						<div class="post">
							<?php the_content(); ?>
						</div>
					<?php
							endwhile;
						endif;
                ?>

But it shows ALL posts of CPT. How I could I do?