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)(11,15)(12,16)(13,18)(14,17)(19,31)(20,27)(21,26)(22,29)(23,28)(24,30)(25,33)(32,39)(34,37)(35,38)(36,40) involution — undirected(2,5)(3,8)(6,7)(9,11)(10,15)(12,19)(13,20)(14,21)(16,25)(17,26)(18,27)(22,32)(23,33)(24,34)(28,31)(29,36)(30,37)(35,40)(38,39) involution — undirected(9,12)(10,16)(11,19)(13,22)(14,23)(15,25)(17,28)(18,29)(20,32)(21,33)(24,35)(26,31)(27,36)(30,38)(34,40)(37,39) involution — undirected(10,17)(15,26)(16,28)(18,30)(25,31)(27,37)(29,38)(36,39) involution — undirected(2,6)(5,7)(9,13,14,24)(10,18,17,30)(11,20,21,34)(12,22,23,35)(15,27,26,37)(16,29,28,38)(19,32,33,40)(25,36,31,39)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.