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