using different images on post title

using different images on post title

please see this https://decentsms.com
you can see there is an animated smiley on the title of every post.

i want to show different smileys for different categorie’s post

for example:

i have uploaded three smilys : smiley1 , smiley2 and smiley3
and having three categories on my blog category1 , category2 and category.

when i post something in category1 i want smiley 1 to appear with the post title which are posted in category1 and when i posted something in category2 then it automatically shows smiley2 with post title posted in category2 …..
how can i do this????????