There are multiple ways of doing this.
1. If you are in the initial stages of room or house construction, you can do one of the following:
1.a. Draw the 7.1 layout, have concealed cable runners, draw the cables and leave it there for later connection.
1.b. Through concealed runners draw the cables, and terminate them at their places using wall plates. Then using small runs of cables with spades on both ends, you can connect the speakers to the terminals on the wall plates.
2. If you are using an existing room, you can use plastic or wooden conduits, and draw the cables along the wall just above the skirts on the bottom. You can draw the cables along the skirts for as long as possible. You may have to use some extra cable length. The conduits will move up the wall only where needed.
3. If you using an existing room, and are ready to dig small holes in the wall, you can sink the conduit and cable into these holes, and cover them later with plaster, white cement or something, and repaint the wall. Nothing will be visible.
4. You can use conduits to draw the cabling as you want, and the cover the whole wall with a sound proofing material so that nothing is visible.
5. You can use wireless receivers and transmitters so that you have no speakers cables drawn at all. A bit expensive, though, and the technology is not yet mature.
6. On the DVD Player, TV, and AVR you can use HDMI cables so that the number of cables is minimal.
Cheers