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