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