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