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