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