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