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