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