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