use GraphViz;

sub as_graph {
    my $haystack = shift;
    my @pitchfork = sort keys %$haystack;
    
    my $g = GraphViz->new();
    
    for my $p (@pitchfork) {
        $g->add_edge($p, $_->{'idref'}) for @{$haystack->{$p}->{'edge'}};
    }
    return $g->as_text;
}

print as_graph( \%s );