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