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