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