What is the stress-strain curve for liquids?

There wouldn't be any. For one thing, the only need to define "stress" is to underline the important fact that a thicker column will probably support more weight than a thinner column.

See what I did there? I said "column". Let me stress (pun not intended) that the term "stress" is not used for fluids. It is a term for use for solids. For liquids, we use "pressure". I hope you meant "pressure vs volumetric compression".

There are many types of liquids, some incompressible, and some compressible. I'll elaborate: every fluid is compressible, but some are more, others less. While studying compressibility, you also need to factor temperature. Hence, we may conclude that each fluid has a unique "stress strain" curve at different temperatures.

there isn't any stress-strain curve for liquids.as liquids are incompressible and do not exhibit the properties of elasticity.!!