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