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