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