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