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