One vertex per element, one color per generator, with an edge from x to x·s.
(2,3)(5,6)(7,12)(8,21)(9,26)(10,29)(11,16)(13,24)(14,27)(15,33)(17,38)(18,48)(19,36)(20,43)(22,34)(23,39)(25,44)(28,45)(30,37)(31,40)(32,42)(35,50)(41,52)(46,59)(47,61)(49,62)(51,60)(53,56)(54,68)(55,63)(57,65)(58,64)(66,67) involution — undirected(1,2,4,3)(5,7)(6,12)(8,22)(9,18)(10,30)(11,19)(13,38)(14,41)(15,43)(16,36)(17,24)(20,33)(21,34)(23,55)(25,51)(26,48)(27,52)(28,49)(29,37)(31,47)(32,50)(35,42)(39,63)(40,61)(44,60)(45,62)(46,56)(53,59)(54,57)(58,67)(64,66)(65,68)(5,8)(6,13)(7,17)(9,23)(10,31)(11,25)(12,34)(14,39)(15,44)(16,40)(18,46)(19,47)(20,51)(21,29)(22,30)(24,33)(26,53)(27,58)(28,57)(32,56)(35,59)(36,60)(37,61)(38,43)(41,66)(42,65)(45,64)(48,63)(49,67)(50,54)(52,55)(62,68) involution — undirected(5,9,11,28)(6,14,16,42)(7,18,19,49)(8,23,25,57)(10,32,33,27)(12,35,36,41)(13,39,40,65)(15,45,29,26)(17,46,47,67)(20,52,30,50)(21,53,44,64)(22,54,51,55)(24,58,31,56)(34,59,60,66)(37,62,43,48)(38,63,61,68)(1,3,4,2)(7,19)(12,36)(17,47)(18,49)(20,30)(22,51)(34,60)(35,41)(37,43)(38,61)(46,67)(48,62)(50,52)(54,55)(59,66)(63,68)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.