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)(11,18)(12,16)(13,22)(14,17)(15,21)(19,24)(20,23)(25,26,30,33,29,31,28,37)(27,34,35,39,36,32,38,40)(3,8)(5,7)(9,11)(10,15)(12,19)(13,20)(14,21)(16,23)(17,18)(22,24)(26,31)(32,34)(33,37)(39,40) involution — undirected(1,3,4,8)(2,5,6,7)(9,12,14,13)(10,16,17,22)(11,19,21,20)(15,23,18,24)(26,31)(32,34)(33,37)(39,40)(2,6)(5,7)(9,12,14,13)(10,16,17,22)(11,20,21,19)(15,24,18,23)(25,27,29,36)(26,32,31,34)(28,38,30,35)(33,40,37,39)(9,13,14,12)(10,16,17,22)(11,20,21,19)(15,23,18,24)(25,28,29,30)(26,33,31,37)(27,35,36,38)(32,39,34,40)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.