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