Jonathan,
We know the flooring here was an early version of Linoleum because, for one thing, they are found the debris field. Ballard got several photos of these 18-inch-square "tiles," a few showing the "star" pattern, too. The pieces that are separated from their Litosilo subflooring are warped and show their 1/4-inch thickness. The underwater photographs show them to be black and white. If the pattern appears blue in your reproduction of my grand staircase painting, then I can't explain that.
The floor in the painting appears warm because of--you got it--the omnipresent incandescent lighting.
Ken