You can ask to ride in any minibus to the Malatya Road and start hitchhiking when you reach the end of the route..
Although the road through Keban is shorter to Sivas than the road through Malatya, there is far less traffic, so it is less recommended.
Take a minibus to the Gümüşkavak Mahallesi which is the last stop before the entrance to Bingöl Road.
East towards Diyarbakir
Take a bus marked Kızılay-Gümüşkavak and get off when the bus reaches the edge of town.