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