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