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