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)(11,19)(12,16)(13,17)(14,18)(15,21)(20,24)(22,23)(25,26,31,29,30,33,28,38)(27,34,36,40,35,32,39,37)(1,3,5,4)(2,6,7,8)(9,11)(10,15)(12,20)(13,22)(14,21)(16,23)(17,24)(18,19)(25,27,30,35)(26,32,33,34)(28,39,31,36)(29,37,38,40)(1,4,5,3)(2,6,7,8)(9,12,14,13)(10,16,18,17)(11,20,21,22)(15,23,19,24)(26,33)(27,35)(29,38)(36,39)(9,13,14,12)(10,17,18,16)(11,20,21,22)(15,23,19,24)(25,28,30,31)(26,29,33,38)(27,36,35,39)(32,40,34,37)(10,18)(15,19)(16,17)(23,24)(25,29,31,33,30,38,28,26)(27,37,36,34,35,40,39,32)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.