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