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