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