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