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