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