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