Graves Runes explained
There's one set of runes for Graves on patch
11.7
that is the clear favorite for LoL players and pros alike. The best Graves Runes on the position 
Jungle are Sorcery as the primary path and
Precision as the secondary path with a pick rate of 90%. Besides runes you should take a look on Graves Build and if you are interested in pro matches take a look at Graves Probuilds. If you want to discuss
Graves then you should visit the champion subreddit.
Primary path on Graves
Sorcery empoweres abilities of Graves and increases the available champion resources. Most of high elo players – and our LoL pros in the the major regions – have agreed that
Phase Rush is the best keystone rune to run on
Graves.
Phase Rush offers more flexibility and options to betake oneself in and out of danger, which can be helpful since that's essentially the main playstyle of Graves. This is usually followed up by taking
Nimbus Cloak,
Absolute Focus and
Waterwalking.
Nimbus Cloak, which grants movement speed upon using a summoner spell, works amazingly well with junglers in particular as they take the shortest cooldown summoner spell,
Absolute Focus grants additional damage while Graves is alomst full health.
Waterwalking grants movement speed in the river, which helps Graves get around the map quicker. The extra damage will also help in those all important dragon and baron fights.
Secondary path on Graves
When it comes to your secondary path, most
Graves players prefer to go with
Precision.
Precision improves attack and sustained damage on Graves troughout the match. On the
Precision path, the best runes for Graves are
Legend: Alacrity and
Triumph.
Legend: Alacrity grants additional attack speed to Graves.
Triumph restores on Graves a part of missing health and award bonus gold, if a champion is killed.