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