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