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)(11,18)(12,22)(13,16)(14,17)(15,20)(19,24)(21,23)(25,26,29,32)(27,33,34,40)(28,36,37,31)(30,38,39,35)(2,5)(6,7)(9,10)(11,18)(12,16)(13,22)(14,17)(15,21)(19,24)(20,23)(28,37)(30,39)(31,36)(35,38) involution — undirected(9,11,14,19)(10,15,17,23)(12,21,13,20)(16,24,22,18)(25,27,29,34)(26,30,32,39)(28,38,37,35)(31,40,36,33)(1,3,4,8)(2,6,5,7)(11,19)(15,23)(18,24)(20,21)(27,34)(30,39)(33,40)(35,38)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.