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