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