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)(11,15,13,16)(12,20,21,23)(17,22,24,19)(25,26)(27,30)(28,32)(29,31)(33,37)(34,39)(35,38)(36,40)(1,3,5,2)(4,7,8,6)(9,11,14,13)(10,15,18,16)(12,19,21,22)(17,23,24,20)(25,27,29,35)(26,30,31,38)(28,33,36,34)(32,37,40,39)(1,4,5,8)(2,6,3,7)(10,16)(11,13)(15,18)(17,20)(19,22)(23,24)(27,33)(28,36)(30,37)(32,40)(34,35)(38,39)(2,3)(6,7)(9,12,14,21)(10,17,18,24)(11,19,13,22)(15,23,16,20)(26,31)(30,38)(32,40)(37,39)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.