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