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