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