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