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