<?php
use Microsoft\Graph\GraphServiceClient;
use Microsoft\Graph\Generated\Models\ListItem;
use Microsoft\Graph\Generated\Models\FieldValueSet;
$graphServiceClient = new GraphServiceClient($tokenRequestContext, $scopes);
$requestBody = new ListItem();
$fields = new FieldValueSet();
$additionalData = [
'Title' => 'Widget',
'Color' => 'Purple',
'Weight' => 32,
];
$fields->setAdditionalData($additionalData);
$requestBody->setFields($fields);
$result = $graphServiceClient->sites()->bySiteId('site-id')->lists()->byListId('list-id')->items()->post($requestBody)->wait();