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