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