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