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