I think Graves is a very powerfull champions due to his great abilitis witch gives him a good damage and also good survivability.

True Grit
Really good passiv. It is good in connection with your runes. You can stay longer in fight or win 1 vs. 1 easier.

Buckshot
Awesome to farm and aslo to make a lot damage on champions. Good in combo with your E spell.

Smoke Screen
I like this spell it is good for attack because you can make it in front of your enemy to slow him but also good if you have to run away!

Quickdraw
Its really good to go into a fight and also to leave a fight. It can help you to jungle too.

Collateral Damage
Really good damage and quite low cooldown. Its awesome in teamfights because you should hit every one and get this way a kill and/or some assists.

Early Game

The first item i buy iswitch cost all your first gold. After it you buy first because the armor penetration and the cooldown is really good in early game.
When able you buy

DORANS BLADE

Helps you dominate the lane early game in the first few levels. A quickdraw followed up by a close range buckshot can be devastating at level 2, and can sometimes draw first blood. The doran's blade helps this a lot.

Youmuu's Ghostblade

This item is really nice because the armor penetration, cooldown and crit chance are really good in early game and also in late game.

BEZERKER GREAVES

I grab these boots for an early increase in attack speed, which I feel is his main early weakness.

PHANTOM DANCER

It is pretty self explanatory as you will need to try to cap your attackspeed late game, you get movement speed to get around the map late game, and get crit chance which helps your proc the 250% crit damage from the infinity edge.

BLOODTHIRSTER

It gives you a lot AD what works really good with your E spell and Youmuu's Ghostblade because you attack really fast and make a lot of damage because of armor penetration.

INFINITY EDGE

When you have this item the game i now quite easy for you because with Bloodthirster and Infinity Edge you AD is REALLY high and the 250% crits should give them the rest.

BLACK CLEAVER

This item works good together with Youmuu's Ghostblade. Now you can kill Tanks really fast too.

I ONLY play withand because you are really slow in early game and then is the slow of exhaust awesome and in late game too. Flash is every time good to attack or to quit a fight.

Pros

- really good damage
- with your E spell you can go through walls
- good AoE damage

Cons

- strats with only 305 movement
- range is not so high
- squishy if ganked while out of combat