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