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