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