At a guess, they're wanting you to draw the various types of numbers in terms of subset-hood.

All the numbers are real numbers, so draw a big circle (or oval, whatever), and label it "Real numbers".

The reals are split between the rationals (fractionals) and the irrationals. So split the circle in half, labelling halves appropriately.

Inside the rationals, you've got the integers (because numbers like "4" can also be written as "4/1", a fraction). So draw a (pretty large) circle inside the "rationals" half and label it.

Inside the integers, you've got the non-negative integers, which are (probably) the whole numbers. (Check your book's definition to see which of "whole" and "natural" includes the number zero.) Draw nested circles, and label.

I could be wrong, but I'd bet good money that the above is what they mean by a "diagram".

Eliz.