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