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