It's confusing at first, but once you actually try to do something with it, it works. Here's a simple script to get you started. I just added a couple of edges, but I think that you'll be able to add some nodes and attributes after awhile.

#!/usr/bin/perl

use strict;
use warnings;
use Graph::Easy qw/as_graphml as_graphml_file/;

my $graph = Graph::Easy->new();

my $graphml_file = $graph->as_graphml_file();
$graphml_file =~ s/\n.*<!--.*-->\n//;

my $graphml = $graph->as_graphml();
$graph->add_edge('orderinfo', 'servicename');
binmode STDOUT, ':encoding(UTF-8)';
print $graphml = $graph->as_graphml();
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