While the point made by user6726 is not wrong with respect to this particular statute, it doesn't address a more basic point about how the supremacy clause works.
Federal criminal laws govern punishments for federal crimes in the federal criminal justice system.
Federal prosecutors bringing federal criminal charges against criminal defendants in the federal criminal justice system can and do secure death penalty sentences against criminal defendants in states where there is no state death penalty.
One recent case where that happened was the Boston Marathon bombing case where a defendant was sentenced to death in federal court for the crime for violation of a federal criminal statute, despite the fact that Massachusetts has no death penalty of its own.
This is not a supremacy clause issue. No state law had to be changed or invalidated because of the existence of the federal law. States law governs how the state criminal justice system works, not the federal criminal justice system.
When we say that a state has abolished the death penalty, we mean that it has abolished it in the state criminal justice system. This doesn't absolutely foreclose the possibility that the death penalty will be imposed in that state on federal charges, although it does make it far less likely that the death penalty will be imposed.
Partially, this is because "blue collar" crime is handled by the states. Partially, this is because out of comity and a concern that juries in states without a death penalty are less likely to vote for a capital sentence, federal prosecutors are less likely to seek the death penalty in a state without capital punishment than in a state with capital punishment.
For example, there are 2,902 people on death row as of 2016, in the U.S. Almost 98% of death penalty convictions that have not yet been carried out were obtained in state courts. Only, 62 involve civilian death penalties imposed in federal courts (mostly in states that have the death penalty) and another 6 involve death penalties imposed in military courts (mostly in states that allow the death penalty or abroad). All of the other cases arose in state courts.