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