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