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