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