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