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