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