This is something that is very hard to achieve purely client side, since it is data and cpu intensive.
About the visualization: graphs are cool, but they should really offer a useful perspective, and I don't see much possible innovations here; a graph of names/pictures is quite useless without any segmentation about interests and activity patterns.
A WoT score like Coracle.social could probably be sufficient to highlight contacts that have a good trust level.
@hodlbod can you share your experience about implementing the WoT?