No right answer to this one, craftworlds are inherently different and there is plenty of room to make up your own idea's. Gav Thorpe's Path of the xxxx series of books have some nice descriptions of craftworld life.
Personally I see them as highly organised and planned, with each dome having a core purpose such as, Military, living quarters, agriculture. This would be a natural extension of the path system as it brings about intense focus on a given area. Certainly smaller craftworlds may share rolls under a single dome, but each would be neatly seperated into its purpose, kind of like Tokyo and their parks.
Basically I imagine the craftworld interiors would be where efficeny and artistic design have harmonised. I would imagine, the wraithbone itself would be a similar colour through out, but in areas like living quaters, vertical gardens would be used to create colour and assist in maintaing air. I don't see any harsh neon signs or any advertising materal being used.
Since Craftworlds are ships, there will be significant periods of time they are not close to a star, so I imagine the domes will have the ability to make use of both natural and artifical light, with the ability to mimic day/night cycles. Given the technology level I would imagine the artifical light would be a close simulation to natural light and not the type of blubs humans would use.
I'm not sure how sterile it would be, given they can travel to different worlds by running through webway portals, let alone convensional ship travel. Assuming a some what similar immune system, they would have to expose themselves to some level natural bacteria and such so they don't become like Quarians from mass effect, but also have quarantine process to avoid nurgle infections.
The craftworld itself would be very clean, no litter, etc. The 3rd book of the Gathering storm describes a couple of different human environments, like the lead up to the temple on terra having petitions and such lining the streets, all those people standing in the queues for that long is going to leave a mess.