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