Yeah, Fresh Air was defiantly in Red Sector and was of course in the core, so the common preconception that all of the interior core is Green Sector ('coz it's full of green stuff) doesn't track very well. It also makes little sense when you consider that as far as dialogue goes, the only thing green sector has been associated with is the ambassadorial suites and the alternate atmosphere sections (the "alien sector".) All the commercial stuff like the Zocalo, the Bazaar, the Casino, Earharts, the conference rooms and even Garibaldi's quarters after he quit as head of security were all in red sector.
However, since Londo's quarters have a view of the core, then at least the oxygen/nitrogen areas of green sector are on the inner surface. Actually, since there was that line in 'The Gathering' about altering the rotation of certain sections to vary the gravity, the most likely place for green secot as far as I can see in that little "bulge" about mid-way down the habitat cylinder. It stands to reason that in order to have a separate carousel within the main centrifuge that can move against the spin to reduce the gravity effect (or with it to increase it) there'd need to be some extra space to accommodate it and some bulky machinery to make it work.
For me the trouble kind of starts when you have the commander's office which also has a view of the main core (or a dodgy painting of it hung outside the window at least.

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I did make a start on charting the rough layout based on the two different displays seen on screen and the version presented in the Security Manual (an unrelable document at the best of times) and the only thing they appear to agree on (aside from the never mentioned and only once seen yellow sector) is that most of the front end in all blue sector, green sector is somewhere in the central core and red sector is in between them. The demarcations are all over the place, brown sector even manages to vanish altogether in one version and it's anyone's guess what's going on in the station's zero-g "spine".
No matter what version you pick there are a number of problems. For instance, as I mentioned above, the supposedly all zero-g yellow sector is seen only once (in 'TKO') and it was most assuredly not without gravity. For one thing, it's where they held the mutai! I think there's also that bit in 'The Gathering' which (if I remember this right) has Sinclair and Lyta taking a shortcut through the alien sector to get to red sector...after *walking* from customs. I suppose it's possible that there would be a smaller "alien sector" closer to the docking bays for short stays (layover for transport crews and the like) which now I think about it might for the zoo-like openness of the place, but it's never addressed as such. Plus cramming a variable gravity ring into the docking sphere might be pushing things a bit.