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