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)(11,15,21,28)(12,16)(13,17)(14,18)(19,26,34,38)(20,27,36,40)(22,29)(23,30)(24,31)(25,32)(33,37,35,39)(2,5)(6,7)(9,11)(10,15,18,28)(12,19)(13,20)(14,21)(16,26,30,38)(17,27,32,40)(22,33)(23,34)(24,35)(25,36)(29,37,31,39)(1,3,4,8)(2,6,5,7)(9,12,14,23)(10,16,18,30)(11,19,21,34)(13,24,25,22)(15,26,28,38)(17,31,32,29)(20,35,36,33)(27,39,40,37)(9,13,14,25)(10,17,18,32)(11,20,21,36)(12,22,23,24)(15,27,28,40)(16,29,30,31)(19,33,34,35)(26,37,38,39)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.