Juggernaut is one of the worst enchants. Unless you have to play straight tank, don't take it. The other enchants are all much more gold efficient and give much more useful stats for their respective champs.
For Shyvana you're definitely going to want Devourer's. Depending on whether you plan to be a heavily aggressive ganker or counterjungle hard, you can go with Skirmisher's Saber to give yourself extra dueling potential, Stalker's Blade to add some much needed utility to your ganks, or Poacher's Knife if you're planning to stack your Devourer using your enemy's jungle as much as yours. I'd suggest either Stalker's Blade or Poacher's Knife, as you're likely going to be building defensive items soon and don't really need the extra dueling potential.
After that, get appropriate boots.
Now you can decide whether you want to be a fighter or an offtank. If you're going the fight route, get to work on a BotRK. If you're going offtank start working on a Hydra. When you've finished these, grab a defensive item. I actually really like Randuin's Omen on her, gives her a useful AoE slow and a heavy chunk of tank stats. After that if you're far ahead, build either the opposite offensive item from what you built earlier, or if you're keeping even build a Maw of Malmortius to both give yourself extra damage and some MR, if you're behind build a Spirit Visage or a Banshee's Veil.
After this, build situational. I've found that some great items for Shyvana are Frozen Mallet, which makes sure once she's on someone they won't be getting away. Mercurial Scimitar can help to counterbalance her weakness to CC. Warmogs works great as a last item since she gets a decent boost to both armor and MR from her ult, and usually doesn't need more than one item for either of those stats to do her job well unless you feel like going full tank.
If you're planning on playing for kills, go 21/9 prioritizing physical damage and taking the 5% attack speed. If you're going to play a bit safer, go 9/21, again prioritizing physical damage and putting defensive masteries where you feel you need them.
Runes I take AS quints, AD runes, armor seals, and MR/level glyphs.
Shyvana's one of my favorite champs. She doesn't have much in the way of utility, but she's one of the few I know I can just relax and do my own thing with and still have it turn out alright because she can fall literally anywhere on the scale of fighter to tank and still be really effective in teamfights. She's who I learned to jungle with, and I jungled with her all through late season 3 and throughout season 4 even with all the changes. She definitely has a slightly harder time now, but the addition of Stalker's Blade helps her early ganks and stacking a Devourer's gets her damage to insane levels in the late game.
Have fun!
jungle?
still good to play in multiple roles?
