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