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