How can I remove the grayscale effect to images?

Please, open your homepage.css (line 194) and replace this code:

.ei-slider-large li img{
    width: 100%;
    filter: url(filters.svg#grayscale); /* Firefox */
        filter: gray; /* IE */
        -webkit-filter: grayscale(1); /* Webkit */
        opacity:1;        
        -webkit-filter: grayscale(100%); /* Chrome 19+ & Safari 6+ */
}

with this:

.ei-slider-large li img{
    width: 100%; 
}