Her and her government could condem attacks on school buses and hospitals and if wanted suggest sanctions on the Saudis but then as UAE and others are also involved so they would also have to be included.
The government could award contracts to BAe and others and encourage a shift from building war machines to other aspects of their expertese like trains for the franchises and make any rail franchise awarded dependamt on using british made equiptment for example.
The government could stop the sanctionioning of the sales of war machines to states with a dodgy record on human rights.
Or course it is political as the government of the day has an international duty to condem masacaring children wherever.
So May can be dragged into the thread as PM, but I agree mentioning jezza opened it up to a left v right bun fight so best to just stop the party political side and critisize the government not for who they but what they are not doing