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