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