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