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