Murraya are generally happy in a variety of soil types but good drainage is critical, along with good soil structure rich in nutrients.
Like other citrus trees soil deficiencies may show up in a yellowing of the leaves. It’s important to improve the soil and regular mulching with chunky mulch which is a good way to help prevent nutrient deficiencies.
Please don't be tempted to pile up the mulch, directly around the stem as this can promote fungal diseases.
Fertilise at least once a year with a premium slow release fertiliser. Water only as needed as I really don't like wet feet.
Over-watered plants may show the same symptoms like dry, thirsty plants. If the soil is moist then the issue is unlikely to be lack of water.