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