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