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