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