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