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