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