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