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)(26,31)(27,35)(28,29)(33,34)(36,37)(38,40)(1,3,5,4)(2,6,7,8)(9,11,13,18)(10,14,16,17)(12,19,20,24)(15,21,22,23)(25,26,28,31,30,33,29,34)(27,32,37,38,36,39,35,40)(11,18)(14,17)(19,24)(21,23)(25,27,29,35,30,36,28,37)(26,32,34,40,33,39,31,38)(1,4,5,3)(2,6,7,8)(12,20)(15,22)(19,24)(21,23)(26,33)(31,34)(32,39)(38,40)(9,12,13,20)(10,15,16,22)(11,19,18,24)(14,21,17,23)(26,33)(27,36)(31,34)(35,37)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.