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)(19,22)(20,21)(23,24)(26,27)(28,35)(32,34)(36,40)(11,15)(14,16)(17,19)(18,22)(20,23)(21,24)(25,26,30,27)(28,33,35,31)(29,34,37,32)(36,38,40,39)(10,13)(14,16)(17,19,21,24)(18,23,20,22)(25,27,30,26)(28,33,35,31)(29,32,37,34)(36,38,40,39)(1,2)(3,5)(4,6)(7,8)(9,10)(11,14)(12,13)(15,16)(17,19)(18,23)(20,22)(21,24)(25,28)(26,31)(27,33)(29,36)(30,35)(32,38)(34,39)(37,40) involution — undirected(1,3,4,7)(2,5,6,8)(9,11,12,15)(10,14,13,16)(17,20,21,18)(19,22,24,23)(25,29,30,37)(26,32,27,34)(28,36,35,40)(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.