Ok went through my pictures and its not surprising that few of the labels - printed and non-printed - last this long. This also includes any markings on the cable itself and of course using service replacements for the details is full of possible issues.
As for you drawing it does not look familiar to me but as said not much to compare it for me right now.
Looking through the pictures of both automatic and the manual transmission cars I see that there are examples and evidence from 67 production of a colored label at or near the firewall seal/grommet and one at or near the drives side frame rail inner surface where the first clamp goes. Not sure adding, at the moment, examples from cars you didn't specify (non-4 speed cars) btu I think the cable is the same in both SB and BB Mustangs and Cougars
So with that all said there are a couple of examples for you to draw from
From a 67 4 speed of one of the members here
Nice protected area that does show some writing on the cable in this location and a color label. May have indicated (ID) the application or just the positioning - that end goes to the speedo end
Don't see any more of the printing on the cable sheave but that may not have held up or maybe never there