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