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