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