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