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