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