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