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