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