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