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