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