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