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