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)(12,18)(13,16)(14,17)(19,23)(20,24)(21,22)(25,26,29,32)(27,30,34,39)(28,35,37,31)(33,40,36,38)(2,5)(6,8)(9,11,14,20)(10,15,17,24)(12,19,13,21)(16,22,18,23)(25,27,29,34)(26,30,32,39)(28,36,37,33)(31,40,35,38)(9,12,14,13)(10,16,17,18)(11,19,20,21)(15,22,24,23)(25,28,29,37)(26,31,32,35)(27,33,34,36)(30,38,39,40)(10,17)(11,20)(16,18)(19,21)(26,32)(30,39)(31,35)(38,40) involution — undirected(9,13,14,12)(10,18,17,16)(11,21,20,19)(15,23,24,22)(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.