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