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