You don' say whether your tree was planted recently or is a well-established one, but it sounds as though the problem is caused by over-watering, as you suspect. A mature Honey Locust is an extremely tough, drought-resistant tree, well fitted to survive long dry spells, but sensitive to over-watering.
If you planted your tree fairly recently. the following watering advice taken from the Draper City Street Tree Guide should help:
• When To Water: Water frequently enough so the soil several inches below the surface is moist without being continually sodden. Soil with adequate moisture for root growth will form a ball when squeezed but will fall apart when bounced on your hand. Crumbling soil is
too dry; sodden soil is too wet. Soil moisture can be assessed by poking a rod into the soil. Rod penetration indicates extent of moist soil.
Resistance indicates overly dry soil… or a rock. A rod coated with mud indicates over watering.
• Watering Frequency: Water every 2 to 4 days if you have planted during the summer in extremely sandy soil. Water less frequently if
you have more clay in your soil, and it is poorly drained, or if you have planted during the early spring or late fall. You must not water so
often that the tree’s roots become waterlogged. Over watering will kill a tree as surely as no water at all. Late fall and early winter water is
essential for trees planted less than two years.
To preserve moisture, it would be a good idea to spread a 3 or 4 inch layer of mulch on the soil around your tree, but make sure that it doesn't come into contact with the trunk.
As yellowing leaves are the only symptom you mention, it's very unlikely that the tree is diseased or suffering from an in insect infestation; however, if its condition doesn't improve, it might be caused by a nutritional deficiency, and this could easily be corrected on the basis of a soil test.