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