Here's a composite image of the whole tech web (including the outer tier of nodes visible on the "minimap"):
(Updated 15 August 2014)
One interesting thing that immediately comes to mind is that the technologies that reward Affinity points (these are the techs with a +symbol on the left in red, yellow or turquoise for Purity, Supremacy and Harmony, respectively) are interspersed throughout the whole web, rather than being segregated in one particular section of the web. In many cases, two different "leaves" of the same node give points for different Affinities.
Also notice that the leaf techs are actually more expensive than the nodes. It seems you'll be able to get to the edge of the web pretty quickly if you ignore the leaf techs.
Spoiler :
(Updated 15 August 2014)
One interesting thing that immediately comes to mind is that the technologies that reward Affinity points (these are the techs with a +symbol on the left in red, yellow or turquoise for Purity, Supremacy and Harmony, respectively) are interspersed throughout the whole web, rather than being segregated in one particular section of the web. In many cases, two different "leaves" of the same node give points for different Affinities.
Also notice that the leaf techs are actually more expensive than the nodes. It seems you'll be able to get to the edge of the web pretty quickly if you ignore the leaf techs.