There are four ways to access the Curve Editor interface: -
1) Perform Menu > Plug-in > Curve Editor > Edit Curve
2) Right click on the Timeline’s Clip or Transform Key and perform Curve Editor > Edit Curve.
3) Right click on the selected object in the viewport and perform Curve Editor > Edit Curve.
4) Use the hot keys (Ctrl+0) to immediately open the Curve Editor interface.