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