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