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