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)(11,14)(12,15)(13,17)(16,21)(18,22)(19,24)(20,23)(25,26)(27,35)(28,31)(29,34)(30,33)(32,38)(36,39)(37,40) involution — undirected(2,5)(6,7)(9,11,13,19)(10,14,17,24)(12,20,21,18)(15,23,16,22)(26,31)(27,36)(29,30)(32,35)(37,38)(39,40)(10,15)(12,21)(14,22)(16,17)(18,20)(23,24)(25,27,28,37)(26,32,31,39)(29,36,30,38)(33,40,34,35)(1,3,4,8)(2,6,5,7)(26,31)(27,37)(33,34)(36,38)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.