Somehow I am able to achieve the functionality by updating the example mentioned in documentation.
I wanted same color for all bars so repeating the same color. Not sure how to pass once for all
public barChartColors2: Color[] = [
{ backgroundColor: '#35A4E8' },
{ backgroundColor: '#35A4E8' },
{ backgroundColor: '#35A4E8' },
{ backgroundColor: '#35A4E8' },
{ backgroundColor: '#35A4E8' },
{ backgroundColor: '#35A4E8' },
{ backgroundColor: '#35A4E8' }
];
public barChartData: ChartDataSets[] = [
{ data: [23, 42, 23, 54], label: 'Sunday', stack:'a' },
{ data: [91, 22, 53, 84], label: 'Monday' },
{ data: [51, 62, 23, 47], label: 'Tuesday' },
{ data: [71, 26, 53, 24], label: 'Wednesday' },
{ data: [51, 72, 33, 94], label: 'Thursday' },
{ data: [11, 32, 43, 54], label: 'Friday' },
{ data: [21, 42, 43, 44], label: 'Saturday' }
];
Stackbliz working demo