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