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