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