The following script will take the derivative of all the plotted datasets in the active graph window. It assumes that these datasets all share the same X values. It then stores the derivative datasets in one new worksheet, named TDerivative.
%W=%H; //store the name of the active window
layer -c; //count stores the number of plotted datasets and %Z stores concatenated names of datasets
GetEnumWks TDerivative; //open new wks and name it TDerivative
copy -x %[%Z,#1] %(%H,2); //copy datasets to the new wks
deriv %(%H,2); //take the derivative of these datasets
wks.col2.label$="Derivative of %[%Z,#1]";
wks.col$(ii+1).label$="Derivative of %[%Z,#ii]";