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