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