While Napoleon is a good judge of character and a very effective dictator, he operates almost entirely through Squealer to promote and excuse his behavior. It is stated explicitly that Napoleon is not a very good speaker, and he prefers to let Squealer do the explaining, as Squealer is adept at twisting words and logic to fit Napoleon's needs. In fact, the betrayal of Boxer is excused entirely by Squealer, who conceals the truth and lies about the kancker's van. On the rare occasions that Napoleon speaks, it is flat and without real emotion; he is a pragmatic speaker, and leaves the emotion to others.
Napoleon was a large, rather fierce-looking Berkshire boar, the only Berkshire on the farm, not much of a talker, but with a reputation for getting his own way.
(Orwell, Animal Farm, msxnet.org)
A speech in Napoleon's voice would be written very simply, without circular logic or educated prose. It would use a deliberate style of speaking, short words and sentences, with a focus on the great goals of the future instead of past mistakes or hindsight. If the truth about Boxer came out, Napoleon would excuse it with a simple lie: "Boxer was working for Snowball all along." This would be supported by the sheep, who would shout down any opposition, and later Squealer would use his circular logic to defend the lie. Napoleon's statement would be no more than a paragraph, perhaps 5-7 sentences. It would start with the importance of supporting the Farm (implicitly, supporting himself) contain the outright lie in the middle, and end with a barely-disguised threat against sedition.