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