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