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