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