I'm surprised you don't get an error, as I am getting this with your code:

syntax error at colors.pl line 31, near "$hash{"
[download]

Anyway, changing your code line with the grep and map as follows:

my %colors = map { $_ => $hash->{$_} } grep { $_ =~ /color$/ } keys %$
+hash;
[download]

my %colors = map { $_ => $$hash{$_} } grep { $_ =~ /color$/ } keys %$h
+ash;
[download]

Output of Data::Dumper on the %colors hash:

$ perl colors.pl
$VAR1 = {
          'test_menu_hl_color' => '#a74d3d',
          'test_widget_color' => '#eee3b7',
          'test_text_color' => '#000000',
          'test_widget_header_color' => '#c6b989',
          'test_menu_color' => '#004d59',
          'background_color' => 'ffffff',
          'test_article_background_color' => '#ceddd2',
          'test_widget_title_color' => '#ffffff',
          'test_menu_text_color' => '#ffffff',
          'test_link_color' => '#31e500',
          'test_headline_color' => '#7b0706',
          'header_textcolor' => 'blank'
        };
[download]