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