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