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