The number of decks will probably not be a concern since you have only a single 'Pole' and five 'Throws' (SP5T). If you had two (Double) Poles and 5 Throws (DP5T) you might have a choice of having both switches share a single Deck or having two Decks with one switch each. A Deck can contain roughly 12 Throws so for Double Throw, Triple Throw, and 4-throw switches you can fit more poles in a small space if you have multiple poles per deck.
For that diagram just pick a SP5T rotary switch.
If you are attaching a knob you probably want one with a "Flatted" shaft. The "Flush" shaft style has to be turned with a screwdriver.