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