This question already has an answer here:
Are there any halachic reasons why Jewish children should not play with toy pigs? They are not eating anything and it does not make them feel like eating treif.
Another question here refers to paintings and general objects, and they are allowed. It might be argued that children should be shielded more strictly. Personally, letting children have pig toys bothers me significantly, but I can't rationalize or "halachize" this feeling.