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