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