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