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