Run the following command to generate sitemaps*:

python sitemap_gen.py --config=config.xml --testing

NOTE:

-- All of the files generated will be under main directory i.e. "public_html"
-- Will generates multiple of sitemap.xml.gz (50,000 urls per file) including the "sitemap.xml"
-- Google Webmaster Tools will allow you to submit the above "sitemap.*.gz" 
-- "sitemap.xml" is good for other web crawlers. DO NOT submit this to Google Sitemap as only 50K urls will be sent.

** USEFUL SITE: https://code.google.com/p/sitemap-generators/wiki/SitemapGenerators