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