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)(11,12)(13,21)(14,18)(15,16)(17,23)(19,24)(20,22)(25,26)(27,31)(28,37)(29,33)(30,34)(32,39)(35,36)(38,40)(1,2)(3,5)(4,6)(7,8)(9,11,15,14)(10,12,16,18)(13,19,23,22)(17,20,21,24)(25,27)(26,31)(28,38)(29,39)(30,35)(32,33)(34,36)(37,40)(1,3,4,7)(2,5,6,8)(10,16)(12,18)(17,21)(20,24)(27,35)(29,38)(31,36)(33,40)(9,12,15,18)(10,11,16,14)(13,20,23,24)(17,19,21,22)(25,28)(26,32)(27,29)(30,39)(31,40)(33,36)(34,37)(35,38)(9,13,15,23)(10,17,16,21)(11,19,14,22)(12,20,18,24)(25,26)(27,36)(28,32)(29,33)(30,34)(31,35)(37,39)(38,40)(9,14,15,11)(10,18,16,12)(13,22,23,19)(17,24,21,20)(25,29)(26,33)(27,28)(30,38)(31,37)(32,36)(34,40)(35,39)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.