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