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)(11,15)(12,23)(13,17)(14,19)(16,27)(18,25)(20,33)(21,30)(22,32)(24,29)(26,35)(28,31)(34,36)(37,40)(38,39) involution — undirected(2,6)(7,8)(9,11,14,22)(10,15,19,32)(12,24,26,38)(13,28,25,21)(16,33,34,40)(17,31,18,30)(20,36,37,27)(23,29,35,39)(1,3,5,4)(2,7,6,8)(9,12,25,36,14,26,13,27)(10,16,17,35,19,34,18,23)(11,20,28,38,22,37,21,24)(15,29,30,40,32,39,31,33)(10,17,19,18)(12,26)(15,30,32,31)(16,23,34,35)(20,37)(24,38)(27,36)(29,33,39,40)(1,4,5,3)(2,7,6,8)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.