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