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