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