You can set a background color for gauge charts within :

...
scaleR:{
   ...
   guide:{
      lineWidth: 2,
      lineColor:'#ff0000', //red lines
      items:[
       {
         backgroundColor:"#ccc
       }
      ]
   }
}

Demo

The demo above sets a backgroundColor for the sections between the red lines.  If you need to create multiple colors this also can be done.

...
scaleR:{
    ring:{
     backgroundColor:'#ED792F' //set orange ring
    },
    guide:{
     lineWidth: 2,
     lineColor:'#ff0000', //red lines
     items:[
       {
         backgroundColor:'#ccc' //grey background
       },
       {
         backgroundColor:'#aaa' //light grey background
       }
     ]
    }

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