One vertex per element, one color per generator, with an edge from x to x·s.
(3,7)(5,8)(26,31)(27,33)(32,38)(34,39) involution — undirected(1,2,4,6)(3,5,7,8)(9,10,14,11)(12,15,19,17)(13,16,21,18)(20,22,24,23)(25,26)(27,28)(29,32)(30,31)(33,35)(34,36)(37,38)(39,40)(1,3)(2,5)(4,7)(6,8)(10,11)(12,19)(13,21)(22,23)(27,33)(28,35)(29,37)(32,38) involution — undirected(9,11,14,10)(12,15,19,17)(13,18,21,16)(20,22,24,23)(25,27,30,33)(26,28,31,35)(29,34,37,39)(32,36,38,40)(1,2)(3,5)(4,6)(7,8)(9,12)(10,15)(11,17)(13,20)(14,19)(16,22)(18,23)(21,24)(25,28)(26,27)(29,36)(30,35)(31,33)(32,34)(37,40)(38,39) involution — undirected(1,3)(2,5)(4,7)(6,8)(9,13)(10,16)(11,18)(12,20)(14,21)(15,22)(17,23)(19,24)(25,29,30,37)(26,32,31,38)(27,34,33,39)(28,36,35,40)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.