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