What is the chromatic polynomial of Peterson graph?

The chromatic polynomial for the Petersen (not Peterson) graph is

pi(z) = (z - 2)* (z - 1)*z*(z^7 - 12*z^6 + 67*z^5 - 230*z^4 + 529*z^3 - 814*z^2 + 775*z - 352).