Presubmit monitoring is provided by Grafana. The dashboard link is https://llvm.grafana.net/dashboards.
Grafana pulls its data from 2 sources: the GCP Kubernetes clusters & GitHub. Grafana instance access is restricted, but there is a publicly visible dashboard:
Cluster metrics are gathered through Grafana alloy. This service is deployed using Helm, as described HERE
Github CI queue and job status is fetched using a custom script which pushes metrics to grafana. The script itself lives in the llvm-project repository: LINK. The deployment configuration if in the metrics_deployment file.