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