make the graph directional
make the graph directional

[#6904]

Signed-off-by: Bohan Chen <c9a015a7f6482b47c219aa2cbd78ba6c88c0a327@pivotal.io>
Co-authored-by: Alex Suraci <925ba519bbf1a06224928b692ef88b93aee946af@gmail.com>

concourse/concourse,concourse/concourse,concourse/concourse,concourse/concourse,concourse/concourse