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