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