(With even representation of colors.)

Sultai, Mardu, Bant, Grixis, Naya
Sultai, Mardu, Bant, Jund, Jeskai
Sultai, Mardu, Esper, Temur, Naya
Sultai, Mardu, Abzan, Jeskai, Temur
Sultai, Esper, Jund, Jeskai, Naya
Sultai, Grixis, Abzan, Jeskai, Naya
Mardu, Bant, Esper, Jund, Temur
Mardu, Bant, Grixis, Abzan, Temur
Bant, Esper, Grixis, Jund, Naya
Bant, Grixis, Abzan, Jund, Jeskai
Esper, Grixis, Abzan, Temur, Naya
Esper, Abzan, Jund, Jeskai, Temur

Code:

Sultai = 'UBG'
Mardu = 'WBR'
Bant = 'WUG'
Esper = 'WUB'
Grixis = 'UBR'
Abzan = 'WBG'
Jund = 'RBG'
Jeskai = 'WUR'
Temur = 'UGR'
Naya = 'WRG'

from itertools import chain, combinations

def powerset(iterable):
    "powerset([1,2,3]) --> () (1,) (2,) (3,) (1,2) (1,3) (2,3) (1,2,3)"
    s = list(iterable)
    return chain.from_iterable(combinations(s, r) for r in range(len(s)+1))

sets = powerset([Sultai, Mardu, Bant, Esper, Grixis, Abzan, Jund, Jeskai, Temur, Naya])
for possible in sets:
	canonical = ''.join(sorted(''.join(possible)))
	if canonical == 'BBBGGGRRRUUUWWW':
		print(possible)