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