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