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