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