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