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