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