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