The turbolift graphic is one from before the Enterprise was rescaled, and wasn't intended to do anything other than sorta show where the bridge was and how it connected to the rest of the Enterprise via a turbolift.
It stands to reason that the bridge was envisioned to be connected to a vertical turbo lift because a) of the cylinder at the exterior of the bridge on the VFX models and b) because there is an optional turbo lift spot on the Season One studio set blueprints at the end of the "Jefferies tube corridor" that would roughly match such a vertical turbo shaft - the only problem is that there is not one TOS episode that ever revealed one of these corridors to have a turbo lift access at this optional spot.
For all we know the casing of this vertical bridge turboshaft could have included all the power lines connecting the bridge and the upper dome to the one below.
Main power lines could split up into smaller and multiple horizontal lines, too small to be displayed on the schematic in the bridge alcove - a turbo lift can not!
If the vertical structures on the bridge alcove schematic (which does have a top view) are turbo lifts, than there are only four turbo shafts aboard he TOS Enterprise
and our protagonists would have to walk to the next vertical shaft - which they apparently hardly ever do in TOS.
And it's somewhat odd that out of these four vertical turbo shafts, two are exclusively devoted to reach the nacelles, although we never saw that happening in any TOS episode, either.
In short, it's possible that Matt Jefferies originally envisioned these structures to be turbo shafts, but the actual turbo lift rides we saw suggest something completely different, IMO.