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