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