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