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