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