Create a File named archive-{yourposttype}.php and Then start tweaking from there. You can style this archive file to your heart’s desire. A very basic template would look like this:
<?php
get_header();
if(have_posts()) : while(have_posts()) : the_post();
the_title();
echo '<div class="entry-content">';
the_content();
echo '</div>';
endwhile; endif;
get_footer();
?>