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