[Solved]-Highcharts custom symbol and colour per node-Highcharts

You need to use nodes options to customize individual node.

nodes: [{
  id: 'n2',
  color: 'yellow',
}, {
  id: 'n3',
  color: 'red',
  marker: {
    symbol: 'triangle'
  }
}, {
  id: 'n4',
  color: 'green',
  marker: {
    symbol: 'square'
  }
}]

Live demo: https://jsfiddle.net/BlackLabel/etug64kw/

API Reference: https://api.highcharts.com/highcharts/series.networkgraph.nodes