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