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