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