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