as dale said. hose it down. dry it. bit of WD40 or GT85 on the frame helps to repel mud. lube the chain every time. jobs a good one. if you have a full susser, wait for it to dry and brush it off. that way you dont get water in the bearings.
hey, cleaning it aside, if you want to protect your bike an awesome tip is to use clear sticky back plastic sheets (WhSmiths, Tesco stationary section stuff) cut to size and applied in areas of the frame that are in the line of fire from debris thrown up by the wheels. you cant see the stuff once its on (because its clear!) and its really good at protecting the paintwork from small stone chips and other potential light damage.
heres an example for you. i actually rode through some spilt paint on the road the other day 😯 i didnt even notice it for a while (daydreaming while riding) and by the time i noticed it had sprayed white dots of paint all over my back and my bike 👿
and although it wiped off fine (thank god) as it hadnt fully dried, the bulk of the spots were on the clear sticky sheet that i have put up the back half of the seat tube, so if i t had dried that could have been simply pulled off meaning it would have been ok.