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