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