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