i think you’d have to use get_posts 5 different times. what about this:
global $post;
$posts = array();
//categories you want to pull latest posts from;
$cats = (1,2,3,4,5);
foreach($cats as $cat):
$args = array( 'numberposts' => 1, 'category' => $cat );
$posts[] = get_posts($args);
endforeach;
if($posts): ?>
<ul>
<?php foreach( $posts as $post ) : setup_postdata($post); ?>
<li><a href="https://wordpress.stackexchange.com/questions/26227/<?php the_permalink(); ?>"><?php the_title(); ?></a></li>
<?php endforeach; ?>
</ul>
<?php endif; ?>
i totally didn’t test this, but I think it might work