One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,7)(4,8)(5,6)(9,10,13,16)(11,17,19,14)(12,20,21,15)(18,22,24,23)(25,26,30,34)(27,31,37,44)(28,38,40,32)(29,33,41,46)(35,42,48,54)(36,49,50,43)(39,51,52,45)(47,55,56,53)(9,11,13,19)(10,14,16,17)(12,18,21,24)(15,22,20,23)(27,35)(28,39)(29,41)(31,42)(32,45)(33,46)(36,50)(37,48)(38,51)(40,52)(43,49)(44,54)(2,6)(7,8)(25,27,29,35,30,37,41,48)(26,31,33,42,34,44,46,54)(28,36,39,47,40,50,52,56)(32,43,45,53,38,49,51,55)(1,3,5,4)(2,7,6,8)(9,12,13,21)(10,15,16,20)(11,18,19,24)(14,22,17,23)(28,40)(32,38)(36,50)(39,52)(43,49)(45,51)(47,56)(53,55)(1,4,5,3)(2,8,6,7)(11,19)(14,17)(18,24)(22,23)(25,28,41,52,30,40,29,39)(26,32,46,51,34,38,33,45)(27,36,48,56,37,50,35,47)(31,43,54,55,44,49,42,53)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.