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