Streptococcus pyogenes is part of the bacteria branch on this tree.  The bacteria have a relationship closer to the archaea than they do to the eukaryotes.  There is a great number of separations within the bacteria branch of the tree.  This proves that even though bacteria are related, they are very different as well.  We can locate Streptococcus pyogenes in the bacillus/clostridium section of this pylogenetic tree.  The closest relative is Streptococcus pneumoniae.  This makes sense because Streptococcus pyogenes can cause pneumonia.  Being closely related to Streptococcus pneumoniae makes sense.  Streptococcus pyogenes also has members of the Enterococcus, Staphylococcus, and Bacillus closely related.      

This picture is from http://www.blackwellpublishing.com/ogunseitan/phyltree.asp#, courtesy of Oladele Ogunseitan, author of Microbial Diversity.