how to change the color in grabcut mask based on a class

Question

here's my image:

i have 2 classes dog and truck i also have their bbox coordinates so i want to create a mask for this image so i applied grapcut algorithm here's my code

img=cv2.imread('dog.jpg')
mask=np.zeros(img.shape[:2],np.uint8)

bgModel=np.zeros((1,65),np.float64)
fgModel=np.zeros((1,65),np.float64)
tmpimage=image
masks=[]
for i in recs:
    cv2.grabCut(img,mask,i,bgModel,fgModel,10,cv2.GC_INIT_WITH_RECT)
    mask2=np.where((mask==2)|(mask==0),0,1).astype('uint8')
    masks.append(mask2)
    #img=image*mask2[:,:,np.newaxis]
finalmask=np.zeros(img.shape[:2],np.uint8)
for i in range(len(masks)):
   finalmask=finalmask+masks[i]
plt.imshow(finalmask)
# plt.colorbar()
#plt.xticks([]),plt.yticks([])
plt.show()

here's the final mask:

what i want to do is i want the area of the dog to have different color than area of the truck in this image both are having the same yellow color