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