how can I visualize the bag-of-words in a scatterplot
I think you should have a look at t-SNE which is a visualization technique based on dimensionality reduction. Wikipedia excerpt:

t-distributed stochastic neighbor embedding (t-SNE) is a machine learning algorithm for dimensionality reduction developed by Geoffrey Hinton and Laurens van der Maaten. It is a nonlinear dimensionality reduction technique that is particularly well-suited for embedding high-dimensional data into a space of two or three dimensions, which can then be visualized in a scatter plot. Specifically, it models each high-dimensional object by a two- or three-dimensional point in such a way that similar objects are modeled by nearby points and dissimilar objects are modeled by distant points.


This paper describes a python implementation of the technique on various word2vec datasets.