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