Improve color palette to avoid using similar colors for different clusters

[valearna]

As suggested by @chris-grove, we should find a better color palette to avoid using similar colors for different words or clusters. As I was mentioning at today's meeting, we are already using a package specifically designed for generating distinct colors (https://www.npmjs.com/package/distinct-colors) for word trends, but it doesn't really work as expected. One possible solution would be to handpick a list of orthogonal colors and always use this list without shuffling the colors every time. This would also provide stable results in terms of color scheme and could help users identify the results quickly.