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