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