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