JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdn.plot.ly/plotly-latest.min.js"></script>
<div id="myDiv"></div>

JavaScript

var trace1 = {
  x: ['giraffes', 'orangutans', 'monkeys'], 
  y: [20, 14, 23], 
  name: 'SF Zoo', 
  type: 'bar'
};

var trace2 = {
  x: ['giraffes', 'orangutans', 'monkeys'], 
  y: [12, 18, 29], 
  name: 'LA Zoo', 
  type: 'bar'
};
var trace2 = {
  x: ['giraffes', 'orangutans', 'monkeys'], 
  y: [12, 18, 29], 
  name: 'LA Zoo', 
  type: 'bar'
};
var trace3 = {
  x: ['giraffes', 'orangutans', 'monkeys'], 
  y: [12, 18, 29], 
  name: 'LA Zoo', 
  type: 'bar'
};
var trace4 = {
  x: ['giraffes', 'orangutans', 'monkeys'], 
  y: [12, 18, 29], 
  name: 'LA Zoo', 
  type: 'bar'
};
var trace5 = {
  x: ['giraffes', 'orangutans', 'monkeys'], 
  y: [12, 18, 29], 
  name: 'LA Zoo', 
  type: 'bar'
};
var trace6 = {
  x: ['giraffes', 'orangutans', 'monkeys'], 
  y: [12, 18, 29], 
  name: 'LA Zoo', 
  type: 'bar'
};

var data = [trace1, trace2, trace3,trace4,trace5,trace6];

var layout = {barmode: 'group'};

Plotly.newPlot('myDiv', data, layout);

var myDiv = document.getElementById('myDiv');
var plotlyData = myDiv._fullData;
var colors="";
for(i=0; i<plotlyData.length; i++){
  var color = plotlyData[i].marker.color;
  colors+=color+"   ";
  console(color);
}
alert("Here are the 6 first colors of plotls: " + colors);