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