This will be a game of trade offs. The first thing I would recommend is that mounting it on a wall may be easier than putting it on the floor since it may simplify lighting. Lighting the map clearly and evenly will be the most important aspect as it will be very noticeable in the end result if it isn't evenly lit. Using two or more strong, well diffused lights of the same type should probably allow for decent coverage of the map, but more light is better than less as long as it is even and the same color.

As far as taking the image, you have two options. You can use a fairly wide lens and capture the whole thing at once, which will produce a natural enough image, but will likely have some amount of distortion from the difficulty in correcting for the angle of view since the corners are coming in to the lens at more of an angle.

The alternative to this is to use a long focal length and take multiple images in a grid and piece them together in to a larger image. This also has the advantage of producing a more detailed image since the resolution will be much higher, but it is more time consuming and still requires that the camera be repositioned to be aiming straight on or distortion will still occur based on the map not being perpendicular to the axis of the camera lens.

Aperture will depend on how straight on you can get things and how far in you zoom. In practical terms, the depth that will be in focus is based on distance from the lens and thus curved, so when shooting something perfectly flat that is filling the view on a wide angle, it's going to move slightly out of focus on the corners if the DOF is too shallow. Adjust the aperture to account as necessary for this. If shooting with the latter method, it should be less of an issue since the entire portion of the image you care about will be on the same plane.