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