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