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