Hi,

Please go to sites/all/themes/md_phoenix/js/front
open file googleMapInit and search to this following code to change the color 

var styles = [
        {
            "featureType": "landscape",
            "stylers": [
                { "visibility": "on" },
                { "color": "#282828" }
            ]
        },{
            "featureType": "poi",
            "stylers": [
                { "visibility": "off" }
            ]
        },{
            "featureType": "road",
            "stylers": [
                { "color": "#383838" }
            ]
        },{
            "elementType": "geometry.stroke",
            "stylers": [
                { "visibility": "off" }
            ]
        },{
            "featureType": "poi",
            "elementType": "labels.text.fill",
            "stylers": [
                { "visibility": "on" },
                { "weight": 8 },
                { "hue": "#ff0000" },
                { "color": "#ffffff" }
            ]
        },{
            "featureType": "landscape",
            "elementType": "labels.text.stroke",
            "stylers": [
                { "color": "#ffffff" },
                { "visibility": "on" }
            ]
        },{
            "featureType": "poi",
            "elementType": "labels.icon",
            "stylers": [
                { "visibility": "on" }
            ]
        },{
            "featureType": "water",
            "elementType": "labels.text.fill",
            "stylers": [
                { "visibility": "off" },
                { "color": "#ffffff" }
            ]
        },{
            "featureType": "water",
            "elementType": "labels.text.stroke",
            "stylers": [
                { "visibility": "on" },
                { "color": "#ffffff" }
            ]
        },{
            "featureType": "water",
            "stylers": [
                { "color": "#004044" }
            ]
        },{
        }
    ]