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)(25,26,31,34)(27,28,30,33)(29,32,39,40)(35,36,38,37)(1,3,5,8)(2,6,4,7)(9,11)(10,14)(12,19)(13,18)(15,23)(16,22)(17,20)(21,24)(25,27,31,30)(26,28,34,33)(29,35,39,38)(32,36,40,37)(9,12)(10,15)(11,17)(13,20)(14,21)(16,24)(18,19)(22,23)(25,28,30,34,31,33,27,26)(29,37,38,32,39,36,35,40)(1,2,5,4)(3,7,8,6)(12,20)(15,24)(17,19)(21,23)(25,29)(26,32)(27,35)(28,36)(30,38)(31,39)(33,37)(34,40)(1,4,5,2)(3,7,8,6)(10,16)(11,18)(15,24)(17,19)(25,27,31,30)(26,33,34,28)(29,38,39,35)(32,36,40,37)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.