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