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