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