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)(11,17)(12,14)(13,21)(15,19)(16,20)(18,24)(22,23)(25,26,28,32,29,31,35,38)(27,30,34,36,33,37,39,40)(1,3,4,8)(2,5,6,7)(10,14)(15,23)(16,21)(17,24)(3,8)(5,7)(9,11,12,18)(10,15,14,23)(13,22,20,19)(16,24,21,17)(25,27)(26,30)(28,34)(29,33)(31,37)(32,36)(35,39)(38,40)(2,6)(5,7)(10,14)(15,23)(16,21)(17,24)(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.