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