One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,6)(4,5)(7,8)(9,10,13,16)(11,17,19,14)(12,20,21,15)(18,22,24,23)(25,26,30,34)(27,31,37,43)(28,32,39,45)(29,33,40,46)(35,41,48,52)(36,42,49,53)(38,44,50,54)(47,51,55,56)(9,11)(10,14)(12,18)(13,19)(15,22)(16,17)(20,23)(21,24)(27,35)(28,38)(29,40)(31,41)(32,44)(33,46)(36,49)(37,48)(39,50)(42,53)(43,52)(45,54) involution — undirected(2,5)(6,8)(25,27,29,35,30,37,40,48)(26,31,33,41,34,43,46,52)(28,36,38,47,39,49,50,55)(32,42,44,51,45,53,54,56)(9,12,13,21)(10,15,16,20)(11,18,19,24)(14,22,17,23)(28,39)(32,45)(36,49)(38,50)(42,53)(44,54)(47,55)(51,56)(1,3,4,7)(2,6,5,8)(11,19)(14,17)(18,24)(22,23)(25,28,40,50,30,39,29,38)(26,32,46,54,34,45,33,44)(27,36,48,55,37,49,35,47)(31,42,52,56,43,53,41,51)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.