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