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