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