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