It’s pretty easy actually in your single-event.php file within the content loop. add this loop where you want your speakers information to show.
$event_title = get_the_title(); // This is the title of the current single event page we are on.
$args = array(
'meta_key' => 'event_name', // the name of your custom field
'meta_value' => $event_title,
'post_type' => 'speakers',
);
$speakers_query = new WP_Query( $args );
if( $speakers_query->have_posts() ) :
echo '<ul>'; // start your section here
while( $speakers_query->have_posts() ) : $speakers_query->the_post();
// echo your speaker content here like name, images, etc.
echo '<li>' . get_the_title() . '</li>';
endwhile;
echo '</ul>'; // end your section here
wp_reset_postdata();
endif;