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