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