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