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