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