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