Node/website architecture visualization
I don't believe there is a Drupal specific option, but you can utilize a module like XML Sitemap:


  The XML sitemap module creates a sitemap that conforms to the
  sitemaps.org specification. This helps search engines to more
  intelligently crawl a website and keep their results up to date. The
  sitemap created by the module can be automatically submitted to Ask,
  Google, Bing (formerly Windows Live Search), and Yahoo! search
  engines. The module also comes with several submodules that can add
  sitemap links for content, menu items, taxonomy terms, and user
  profiles.


and then use a number of third party online or software based options for visualising xml data.  A quick search in google yielded a number of options for 'visualise sitemap'