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