There was a Graphics Standards Manual at NASA, you can learn about it and download the PDF at NASA Graphics Standards Manual | NASA.
Some folks made a physical re-issue of the manual as a hardcopy book, which may be ordered at 1975 NASA Graphics Standards Manual.
I have three extra copies I do not wish to store any longer. To claim it, please respond here (so others know they’ve been claimed) and we can email about shipping.
Also, if shipping is very expensive from Oakland, CA, USA, please cover most of that.