How to make the network graph more balanced?

I want to illustrate the network graph of a person. The idea is that the network consists of 3 types of people, therefore there are 3 kinds of color and face. The persona is one of the types, so its circle is largest and in the center. The sizes of the circles represent the importance of that person to the persona. So the first level circles is 50% smaller than the center circle, and the second level is 50% smaller than the first level circles.

Given a set of surrounding colors, how to find a good color template?

This is a map of topics the I cover in my project. The topics are segmented in different stages, and I would like to have your advice on how to color the segments. I check the color wheel to find a suitable color template, but I don’t see one really fit with the yellow sky and blue water. In the end I set them while altogether. I satisfy with this, but since I want to learn more about color theory, if you can recommend a good template that would be nice.