The maps you see in the monoliths are enamel and it's doubtful they persist in paper form (i.e., other than a by-product) at any point in the manufacturing process.
For reference purposes, the maps under discussion here look like this...

I wrote to the contractor enquiring about the possibility of acquiring PDF versions, this is their (redacted) response...

The relevant portions are...
...We do indeed manufacture the Legible London totems, including the
printing of the maps ... we therefore cannot sell the maps to
others...
These maps are not available in the retail markets. However, this may change where smaller portions of the maps are offered as fold-out brochures. I will update this answer when that happens.

Regarding the 'complete base map'... Although not 'Legible London', I have actually watched the TfL design team change the tube map. Indeed this 'base map' is a huge PDF file and they apply the changes using Adobe Acrobat and Adobe Illustrator. It's then shipped off to their printing shop with some written specifications. Seeing that TfL has embedded skill sets for doing this, it's likely that they use the same technique for 'Legible London' and that contracted products are provided to them in PDF format. But again these are controlled assets and not (as yet) available in the retail market.
TfL = Transport for London. As mentioned in comments, TfL is a company incorporated under the Companies Act 2006 and hence their products are not generally public domain.