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