Do something fancy with colours.

app/Generator/Chart/Bill/ChartJsBillChartGenerator.php

@@ -15,6 +15,7 @@ namespace FireflyIII\Generator\Chart\Bill;
 
 use FireflyIII\Models\Bill;
 use FireflyIII\Models\Transaction;
+use FireflyIII\Support\ChartColour;
 use Illuminate\Support\Collection;
 
 /**
@@ -37,7 +38,7 @@ class ChartJsBillChartGenerator implements BillChartGeneratorInterface
             'datasets' => [
                 [
                     'data'            => [round($unpaid, 2), round(bcmul($paid, '-1'), 2)],
-                    'backgroundColor' => ['rgba(53, 124, 165,0.7)', 'rgba(0, 141, 76, 0.7)',],
+                    'backgroundColor' => [ChartColour::getColour(0), ChartColour::getColour(1)],
                 ],
 
             ],

app/Support/ChartColour.php

@@ -0,0 +1,56 @@
+<?php
+/**
+ * ChartColour.php
+ * Copyright (C) 2016 thegrumpydictator@gmail.com
+ *
+ * This software may be modified and distributed under the terms of the
+ * Creative Commons Attribution-ShareAlike 4.0 International License.
+ *
+ * See the LICENSE file for details.
+ */
+
+declare(strict_types = 1);
+
+namespace FireflyIII\Support;
+
+/**
+ * Class ChartColour
+ *
+ * @package FireflyIII\Support
+ */
+class ChartColour
+{
+    public static $colours
+        = [
+            [53, 124, 165],
+            [0, 141, 76],
+            [219, 139, 11],
+            [202, 25, 90],
+            [85, 82, 153],
+            [66, 133, 244],
+            [219, 68, 55],
+            [244, 180, 0],
+            [15, 157, 88],
+            [171, 71, 188],
+            [0, 172, 193],
+            [255, 112, 67],
+            [158, 157, 36],
+            [92, 107, 192],
+            [240, 98, 146],
+            [0, 121, 107],
+            [194, 24, 91],
+        ];
+
+    /**
+     * @param int $index
+     *
+     * @return string
+     */
+    public static function getColour(int $index): string
+    {
+        $index = $index % count(self::$colours);
+        $row   = self::$colours[$index];
+
+        return sprintf('rgba(%d, %d, %d, 0.7)', $row[0], $row[1], $row[2]);
+    }
+}