Site Map can be retrieved in two ways. (None of them actually are designed to be human-readable but they can use)
1- XML
Liferay Portal makes this very simple for administrators by generating the sitemap XML automatically for all public web sites.
2- LAR file (Liferay Archive)
The Export / Import tab allows you to export the pages you create into a single file, called a LAR (Liferay Archive). You can then import this file into any server running Liferay, and all of your pages will be copied.
Using the first format, you can generate any kind of human-readable format (like trees), and attaching the second file, you can send the information, and others can upload it.
I hope it works :)
Quotes are from Liferay documentation