The graph show total number of deaths from any reason. It would be hard to say how many of those are related to construction and almost impossible to asses how many can be classified as work related.
Still there are lot of reports say that most workers especially in construction do work in bad conditions, very high temperatures, high humidity, low quality water and bad accommodation and medical services. Personal safety and well being of the workers doesn't seem like priority, so it is obvious that mortality rate is much higher that that in US. It is also worth to note that bad working conditions can lead to developing many illnesses including ones that can lead to premature death weeks, months and even years after those immigrants leave the country and those would not be covered by this statistics at all.