LM78XX voltage regulators
You can place the switch on the input of the regulator, and duplicate the regulator and the components after it.
A few remarks, though. The input says &lt; 24V AC/DC. I presume this comes from a transformer, so it will be up to 24V AC. Rectified that will be \$24V \times \sqrt{2} - 2V = 32V\$  . That's a lot, and especially the LM7805 will get hot: it would have to dissipate 27W at 1A, that won't do! Choose a transformer in function of the 12V. It will need 15V at the input, so that's 12V AC minimum. Especially the 7805 will still need cooling.
Then 25V for the input electrolytic capacitor is also OK (it wouldn't be for 24V AC!).  

All this said, there are much nicer solutions. The LM317 is also a three-legger but has a variable output voltage, so if you use a potmeter you can vary the output voltage continuously. If you want you can still use a switch to get 5V or 12V directly: so, a switch 5V-12V-variable.  

edit (some refinements)
First the input capacitor. For a 1A supply (a minimum value for a bench top supply) the 470\$\mu\$F won't do. My rule-of-thumb is 2000\$\mu\$F/A, so use a 2200\$\mu\$F type. You also want a smaller cap parallel to it to suppress glitches (the 2200\$\mu\$F is not good at this). I would place a 1\$\mu\$F ceramic there.
You mention this application example in your comment:  

  

The capacitor gives a better ripple rejection. Ripple is the variation which remains after the rectified voltage has been smoothed out by the capacitor:  

  

The LM317 has already better ripple rejection than the LM78xx, but you get this almost for free, so I would add it.

edit2 (putting on my product manager's hat)
Especially when you're working with microcontrollers you'll want to have a fixed power supply available for that at any time, apart from the adjustable. Most microcontrollers work at 3.3V or 5V. Probably best thing would be to feed two regulators parallel from the input capacitor: one which can switch between 3.3V and 5V, and one adjustable through a potmeter. The adjustable can then be used for peripherals like small motors and relays.