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