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