Do you know which species it is? There are Daylilies that bloom in early spring, mid-late spring, early summer and late summer. You may have one that is a later bloomer than you thought. Also, check the water in the pot. Yellow leaves can be cause by too much water and also by too much plant food.
Make sure the pot has really good drainage and see how soggy the soil is now. You might want to move it so it doesn't get more rain until the soil dries out a bit. In the ground the water will evaporate from the ground surface and drain away from the roots but in a pot it just sits there, sometimes causing roots to rot but definite harming a non-bog plant that has to stay in boggy conditions. If the soil is staying soggy, dig up the bulbs and leave them out of the soil for a couple of days to dry some. Then repot, possibly into a clay pot that's won't hold in the moisture like a plastic one will. Growers have perfect growing conditions to force plants to bloom a little earlier in the season so they attract the attention of buyers. But if they are staying too wet, the stress could set the bloom period back this year. It may not bloom this year but it should survive to try again next year.
