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