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