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