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