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)(11,19,22,33)(12,23,25,38)(13,26,27,17)(15,28,29,21)(16,31,32,24)(20,35,37,30)(34,39,40,36)(1,2)(3,7)(4,6)(5,8)(9,11,13,21,14,22,27,28)(10,15,17,19,18,29,26,33)(12,20,24,36,25,37,31,39)(16,30,23,34,32,35,38,40)(2,6)(3,4)(7,8)(15,29)(19,33)(30,35)(34,40) involution — undirected(1,3,5,4)(2,7,8,6)(9,12,13,24,14,25,27,31)(10,16,17,23,18,32,26,38)(11,20,21,36,22,37,28,39)(15,30,19,34,29,35,33,40)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.