code: private function writeSheetLayout()
      {
          if (!$this->phpSheet->isTabColorSet()) {
              return;
          }
  
          $recordData = pack(
              'vvVVVvv',
              0x0862,
              0x0000, // unused
              0x00000000, // unused
              0x00000000, // unused
              0x00000014, // size of record data
              $this->colors[$this->phpSheet->getTabColor()->getRGB()], // color index
              0x0000        // unused
          );
  
          $length = strlen($recordData);
  
          $record = 0x0862; // Record identifier
          $header = pack('vv', $record, $length);
          $this->append($header . $recordData);
      }
docs: Write SHEETLAYOUT record.