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