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