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