The default Joomla!® sitemap is created as a Navigation Module.
There is, in the opinion of UsingJoomla.com, another SiteMap generator in the form of a component that goes above and beyond.
UsingJoomla.com recommends the use of OSmap from JoomlaShack.
OSmap comes in the form of a Component and 2 versions are available - Core and Pro.
The core version provides a basic yet quite versatile SiteMap.
The Pro version provides a few additional features, including component support from the developers.
The SiteMap is created in four forms: Human readable (HTML), Search Engine readable form (XML), Image Sitemap for Google, and a Google News sitemap.
The Human readable version is the version you link to on your website, and the Search Engine readable version is what you submit to Search Engines such as Google.
An example of human readable, such as used on UsingJoomla.com can be found via the SiteMap menu item above. As you may have noticed - the SiteMap layout is better presented then the default Joomla SiteMap module.
Not normally needed to be seen by humans here is an example of the Search Engine Sitemap.