Hi will someone please tell me if I score 40,800 rank in keam 2019 , in which all engineering can I get admission?

Unless you have a category reservation like SC or ST then you cannot get into a government college.
You have a very good chance to get into self financing colleges, as they do not really have that much of an admission criteria and you can easily get there with your rank.
Some of the government controlled colleges also so have accepted closing ranks that were near to yours during previous years so you can also try for those type of colleges.
Hope this helps!