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