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