First, you have to perform a serial of transmission spectrum calculations of a device system at different bias voltage V_ds in the range shown in the figure [ e.g., V_ds increases from -1.2 V to 1.2 V in an interval of 0.2 V].
Second, arrange and print out the data in the following format for the transmission coefficient as functional of E at different V_ds:
E[1]_1 V_ds [1] transmission coefficient[1]_1
.......
E[1]_n V_ds [1] transmission coefficient[1]_n
E[2]_1 V_ds [2] transmission coefficient[2]_1
.......
E[2]_n V_ds [2] transmission coefficient[2]_n
E[m]_1 V_ds [m] transmission coefficient[m]_1
.......
E[m]_n V_ds [m] transmission coefficient[m]_n
Third, for the 3 dimensional data in the above format, you can use the matplotlib of python and the GNUPLOT to draw a contour plot for generating plot as you desired. For the details, you had better ask the author of the source of that figure.