First you will get your current location using the code below -
CLLocationCoordinate2D myLocation = self.mapView.myLocation.coordinate;
You can then use GMSMarker to indicate your current location with an image or color.
GMSMarker *marker = [[GMSMarker alloc] init];
marker.position = CLLocationCoordinate2DMake(-33.86, 151.20);
marker.title = @"Sydney";
marker.snippet = @"Australia";
marker.icon = [UIImage imageNamed:@"point1.png"];
marker.map = self.mapView;
Hopes for the code will help you.