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