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