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