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