Apologies Andy, I misread your post.
I really love these visual puzzles and probably take way too many liberties with the preamble but, for the record, I erased all the letters, bar the pairs required for the outline, and connected them using a very fine black pen. I drew the line starting at the centre of 1a and followed it to both the top and bottom of the N at 11 to give dimension to and better illustrate the original work, then carried on from there, using curves and straight lines as appropriate. Regards the colouring, I shaded the 2 outer columns at 1a and 10d one colour and everywhere between those and the outline of the CS another, including the squares above it, leaving only the interior of the CS completely blank. I'm currently undecided about the 2 central squares at the bottom in 37a because the pictures online show they're black, but that that doesn't fit with the title.
The end result really does look good, even if I say so myself, and helps illustrate what a great piece this is and why it has such enduring appeal 😀