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