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