orderby => question

On this site https://nurdit.com/spungold/project/wogam-now-then/ Where it says ‘You Might Also Like’ is there a way to orderby genre/category rather than ‘rand’ to show other portfolios of the same category?

<!--Portfolio-->

<section id="portfolio">

	<div class="wrap clearfix">

		<h1><?php _e( 'You Might Also Like', 'mighty' ); ?></h1>

		<?php
			if( is_singular( 'portfolio' ) ) :
				$current = $post->ID;
				$loop = new WP_Query( array( 'post_type' => 'portfolio', 'posts_per_page' => 3, 'orderby' => 'rand', 'post__not_in' => array( $current ) ) );
			else :
				$loop = new WP_Query( array( 'post_type' => 'portfolio', 'posts_per_page' => 3, 'orderby' => 'rand' ) );
			endif;

			$count = 1;
		?>

	<?php if ( $loop->have_posts() ) : ?>

		<div class="clearfix">

		<?php while ( $loop->have_posts() ) : $loop->the_post(); ?>

			<!-- Article -->
			<article class="post<?php if( $count %3 == 0 ) { echo ' last'; }; $count ++; ?>" itemscope="itemscope" itemtype="https://schema.org/CreativeWork" itemprop="associatedArticle">

				<?php if ( has_post_thumbnail() ) : ?>

					<a href="<?php the_permalink(); ?>" title="<?php _e( 'View more of', 'mighty' ); ?> - <?php the_title(); ?>" rel="bookmark">
						<?php the_post_thumbnail( 's' ); ?>
						<div class="overlay"></div>
						<span><?php the_title(); ?></span>
					</a>

				<?php endif; ?>

			</article>

		<?php endwhile; ?>

		</div>

		<?php wp_reset_postdata(); ?>

	<?php endif; ?>

	</div>

</section>