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