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