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