One vertex per element, one color per generator, with an edge from x to x·s.
(9,10)(11,19)(12,13)(14,17)(15,18)(16,22)(20,23)(21,24)(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(2,5)(3,7)(9,11)(10,16)(12,20)(13,21)(14,23)(15,22)(17,24)(18,19)(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) involution — undirected(1,2)(3,6)(4,5)(7,8)(9,12,15,17)(10,13,18,14)(11,20,22,24)(16,21,19,23)(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)(2,5)(6,8)(9,13,15,14)(10,17,18,12)(11,21,22,23)(16,24,19,20)(26,33)(27,37)(32,46)(34,43)(36,51)(38,50)(39,54)(52,56)(1,3,4,7)(2,6,5,8)(9,14,15,13)(10,17,18,12)(11,21,22,23)(16,20,19,24)(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.