I see this same style of image graphs, usually .png that is used in many routers, CMS, control panels, etc, what actual script generates these ?
RRDtool

Plesk panel health monitor. Edit: I see Plesk also uses rrdtool

Cacti graphs

I see this same style of image graphs, usually .png that is used in many routers, CMS, control panels, etc, what actual script generates these ?
RRDtool

Plesk panel health monitor. Edit: I see Plesk also uses rrdtool

Cacti graphs

That specific graph is generated with RRDTool.
RRDTool is a round robin database for storing time series data. It also includes a tool to generate graphs from that data.