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