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