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