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