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