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