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