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