After doing some research, it is hard to set the hover colorof DataGridViewComboBoxCell directly.
And I have a suggestion you can refer to.
You can try to customize combobox and add it to datagridview, which has the same effect as DataGridViewComboBoxCell.
This thread may help you.
Then you can get windows system color.
In winforms, you can use System.Drawing.SystemColors.
More details you can refer to this thread.