Dataset of grad admission acceptance rate based on undergrad school I am looking for datasets that would list the acceptance rates of graduate school applicants based on their undergrad schools. I.e. X % of students from undergraduate school Y applying to graduate school Z are admitted. Ideally, the dataset should also indicate the number of applicants.

I am mostly interested in graduate schools based in the United States, and computer science departments.
The specific dataset you seek is likely unavailable because of concerns about personal identifying information and the confidentiality of the process.  The number of applicants from small colleges or to small CS programs in any given year is in many cases too low for effective anonymity.   

Many good undergrad programs will tell you about where their graduates went in terms that they are comfortable with, e.g. "x% went to grad school;" some will even list exactly which graduates went where - usually with the permission of both the graduate and the department head.  I don't think anybody's gathered this into a single dataset. 

However, certain aspects of your curiosity may be satisfied by graphs and compiled data from a step later down the line, about which universities hire grads from which other universities for their CS faculty.  That kind of information can be found here (compiled by Jeff Huang and his students at Brown University, analyzed by Jürgen Pfeffer at Carnegie Mellon):

(source: pfeffer.at)