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