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