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