I believe providing a draft letter is absolutely fine, provided you ask your recommender if they would welcome that, dropping the idea if they do not, and make it perfectly clear that they can edit it or throw it out, as they see fit.
In fact, only YOU really know what your entire application portfolio looks like, and only YOU really know what part of your portfolio you'd like each letter writer to validate, so drafting a letter actually makes sense.
You're not "sending it to them for approval". They are the letter writers, and they get to do whatever they want to do with your draft. In case there is any miscommunication in your original question, it is NOT OK to send in the recommendation on their behalf, posing as the recommender. That's a very serious falsification.