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