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