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