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