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