I found a way to do this without using any plugin. I just used This Article
mixed with this This Article
to get some code like this one:
<?php foreach((get_categories('exclude=1,4,6,7')) as $cat) {
echo '<a href="https://example.com' . $cat->category_nicename . '"><img src="https://example' . $cat->category_nicename . '.png" width="178" height="28" alt="' . $cat->cat_name . '" /></a> ';
} ?>
So with this code, we can display a picture for the category that links to its category page, instead of showing the category’s title and the typical link.
Hope it helps!