Some people may find this flippin' ninja as a non-jungler, but here we go!
My personal perspective and build for Shen.

The reason I chose to use AP Shen is because all of his skills are based off of ability power! Why let such an amazing champion go to waste? Using this build, you are not only tanking, but providing a sufficient source of damage to the enemy team, with some support items to help your team out. With this build, your team will absolutely love you.

Start off with Boots of Speed and 3 health potions. Build yourself a heart of gold(HoG) and finish your Mercury Treads. After that, rush the Wit's End, starting with the Magic resist portion. To be more team-friendly, build an Aegis of Legion if your support doesn't have it as it gives nice boosts to the team. As the game progresses, and you may either be fed or feeding, you can decide whether you want your Rylai's Crystal Scepter or your Randuin's Omen. As you choose one, the next will definitely be the one you did not already build. The last itme you should build would be your Abbysal Scepter, for the extra ability power and magic resists(also the nice derease for the enemy players).

Some may ask why I do not include Madred's Razors in my build, my simple answer being that it slows the build down, and late game you do not need them. You would end up selling them(in other words, losing money).

Wit's End on Shen? Oh, yes! It is such an amazing item, it makes jungling a lot quicker as well. For shen, as you attack, not only does it stack magic resist(in fights very useful), it damages the enemy. This item is just as effective late game.

Rylai's and Abbysal on Shen? Yes, yes! Clearly, my title explains that I have included ability power in this build, as all of Shen's abilities scale off of ability power. Ryali's gives a nice slow debuff when using skills on an enemy team, and a nice amount of hp for the tank part. Abbysal scepter gives MR, and ability power. This is not only a tanking and support item, it gives you damage!!

http://www.mobafire.com/league-of-legends/item-purchase-planner#&item=82-68-77-85-102-34

As this is a jungling build, you would definitely use smite. Personally, I run with Smite and Flash because it can get you out of sticky situation+Taunt is delicious.

You may also choose to use ghost, for the speed boost if you don't use flash.
Another one I often observe is exhaust, this may also be a very viable option, as it is amazing for ganks.

Base these options on your personal preferences.

Here we go. Using these runes, you may be able to finish your wolf camp before blue spawns(1:55). You may need to pop a health potion during blue, but remember to get a good leash from your teammates. Head to wraiths, then golems. Do not waste smite. Go obtain the Red buff using your smite. Gank a lane if possible. Rinse and repeat in any order when the game has progressed.

Shen isn't the greatest jungler, so counter jungling isn't as easy. My best tip is to abuse your wards. Place them at key points like the enemy Red or Bluee buff, and of course Baron and Dragon when they spawn.

One thing I notice a lot in players is that when ganking, Shen's tend to start off with their taunt. I find this extremely stupid and also a waste because why not do as much damage as possible before they run, and as they try to escape, then use your taunt to catch them and finally secure a kill? I find that the most effective way to gank.

Oh, and as AP Shen, your ultimate.... is beautiful.

Shen could be a great jungler, and an outstanding ganker. With that taunt, you will make the enemy cry if used properly. Go out there and knock em' dead!

Dat flippin' ninja!