You could make use of a recursive traverse subroutine like so: 
use CGI;
my $cgi = new CGI;

my $our_hash = {
    'Cows' => {
        'Brown' => undef,
        'Green' => undef,
        'Strawberry' => {
            'Spotted' => undef,
            'Solid' => undef
        },
        'Orange' => undef
    },
    'Dogs' => {
        'Purple' => {
            'Spotted' => undef,
            'Solid' => undef
        }
    }
};

use Data::Dumper;

print $cgi->header();
print "<html><title>Page Title</title><body>";

#print Dumper($our_hash);

sub traverse_hash {
  my $ahash = $_[0];
  my $r;
  print "<ul>\n";
  for (keys %$ahash) {
    $r = $ahash->{$_};
    print "<li> $_\n";
    traverse_hash($r)
      if (ref $r eq 'HASH');
  }
  print "</ul>";
}

$DB::single = 1;
print traverse_hash($our_hash);
$DB::single = 1;

print "</body></html>";

[download]
Which yields this output: 
Content-Type: text/html; charset=ISO-8859-1

<html><title>Page Title</title><body><ul>
<li> Dogs
<ul>
<li> Purple
<ul>
<li> Spotted
<li> Solid
</ul></ul><li> Cows
<ul>
<li> Green

<li> Brown
<li> Strawberry
<ul>
<li> Spotted
<li> Solid
</ul><li> Orange
</ul></ul>1</body></html>

[download]
Update: darn! merlyn beat me to it ;-)...

_____________________ 
# Under Construction

[download]

In reply to Re: Hash to HTML display by vladb
in thread Hash to HTML display by Anonymous Monk

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.