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