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