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