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