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