I have installed this plugin before without issue. However, I have a fresh install, and after activating this plugin, the edit screen is not available under 'Settings'.
I am using a custom theme, so I have taken the usual steps of deactivating all plugins and reverting to TwentyEleven theme, but when activating the Google XML Sitemap plugin ONLY, I still get no edit screen.
When I visit the URL (mysitename/sitemap.xml) I get an unstyled (but accurate) listing of all pages - even though the xml file doesn't appear to be present in my root directory.
What else can I try - have I forgotten to do something? I assume it's an issue at my end - this is always such a reliable plugin.