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