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